Antibody tests for identification of current and past infection with SARS‐CoV‐2

Jonathan J Deeks; Jacqueline Dinnes; Yemisi Takwoingi; Clare Davenport; René Spijker; Sian Taylor-Phillips; Ada Adriano; Sophie Beese; Janine Dretzke; Lavinia Ferrante di Ruffano; Isobel M Harris; Malcolm J Price; Sabine Dittrich; Devy Emperador; Lotty Hooft; Mariska MG Leeflang; Ann Van den Bruel; Cochrane COVID-19 Diagnostic Test Accuracy Group

doi:10.1002/14651858.CD013652

. 2020 Jun 25;2020(6):CD013652. doi: 10.1002/14651858.CD013652

Antibody tests for identification of current and past infection with SARS‐CoV‐2

Jonathan J Deeks ^1,^8,^✉, Jacqueline Dinnes ^1,⁸, Yemisi Takwoingi ^1,⁸, Clare Davenport ^1,⁸, René Spijker ^2,⁵, Sian Taylor-Phillips ^1,³, Ada Adriano ¹, Sophie Beese ¹, Janine Dretzke ¹, Lavinia Ferrante di Ruffano ¹, Isobel M Harris ¹, Malcolm J Price ^1,⁸, Sabine Dittrich ⁴, Devy Emperador ⁴, Lotty Hooft ⁵, Mariska MG Leeflang ^6,⁹, Ann Van den Bruel ⁷; Cochrane COVID-19 Diagnostic Test Accuracy Group¹

Editor: Cochrane Infectious Diseases Group

PMCID: PMC7387103 PMID: 32584464

Abstract

Background

The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) virus and resulting COVID‐19 pandemic present important diagnostic challenges. Several diagnostic strategies are available to identify current infection, rule out infection, identify people in need of care escalation, or to test for past infection and immune response. Serology tests to detect the presence of antibodies to SARS‐CoV‐2 aim to identify previous SARS‐CoV‐2 infection, and may help to confirm the presence of current infection.

Objectives

To assess the diagnostic accuracy of antibody tests to determine if a person presenting in the community or in primary or secondary care has SARS‐CoV‐2 infection, or has previously had SARS‐CoV‐2 infection, and the accuracy of antibody tests for use in seroprevalence surveys.

Search methods

We undertook electronic searches in the Cochrane COVID‐19 Study Register and the COVID‐19 Living Evidence Database from the University of Bern, which is updated daily with published articles from PubMed and Embase and with preprints from medRxiv and bioRxiv. In addition, we checked repositories of COVID‐19 publications. We did not apply any language restrictions. We conducted searches for this review iteration up to 27 April 2020.

Selection criteria

We included test accuracy studies of any design that evaluated antibody tests (including enzyme‐linked immunosorbent assays, chemiluminescence immunoassays, and lateral flow assays) in people suspected of current or previous SARS‐CoV‐2 infection, or where tests were used to screen for infection. We also included studies of people either known to have, or not to have SARS‐CoV‐2 infection. We included all reference standards to define the presence or absence of SARS‐CoV‐2 (including reverse transcription polymerase chain reaction tests (RT‐PCR) and clinical diagnostic criteria).

Data collection and analysis

We assessed possible bias and applicability of the studies using the QUADAS‐2 tool. We extracted 2x2 contingency table data and present sensitivity and specificity for each antibody (or combination of antibodies) using paired forest plots. We pooled data using random‐effects logistic regression where appropriate, stratifying by time since post‐symptom onset. We tabulated available data by test manufacturer. We have presented uncertainty in estimates of sensitivity and specificity using 95% confidence intervals (CIs).

Main results

We included 57 publications reporting on a total of 54 study cohorts with 15,976 samples, of which 8526 were from cases of SARS‐CoV‐2 infection. Studies were conducted in Asia (n = 38), Europe (n = 15), and the USA and China (n = 1). We identified data from 25 commercial tests and numerous in‐house assays, a small fraction of the 279 antibody assays listed by the Foundation for Innovative Diagnostics. More than half (n = 28) of the studies included were only available as preprints.

We had concerns about risk of bias and applicability. Common issues were use of multi‐group designs (n = 29), inclusion of only COVID‐19 cases (n = 19), lack of blinding of the index test (n = 49) and reference standard (n = 29), differential verification (n = 22), and the lack of clarity about participant numbers, characteristics and study exclusions (n = 47). Most studies (n = 44) only included people hospitalised due to suspected or confirmed COVID‐19 infection. There were no studies exclusively in asymptomatic participants. Two‐thirds of the studies (n = 33) defined COVID‐19 cases based on RT‐PCR results alone, ignoring the potential for false‐negative RT‐PCR results. We observed evidence of selective publication of study findings through omission of the identity of tests (n = 5).

We observed substantial heterogeneity in sensitivities of IgA, IgM and IgG antibodies, or combinations thereof, for results aggregated across different time periods post‐symptom onset (range 0% to 100% for all target antibodies). We thus based the main results of the review on the 38 studies that stratified results by time since symptom onset. The numbers of individuals contributing data within each study each week are small and are usually not based on tracking the same groups of patients over time.

Pooled results for IgG, IgM, IgA, total antibodies and IgG/IgM all showed low sensitivity during the first week since onset of symptoms (all less than 30.1%), rising in the second week and reaching their highest values in the third week. The combination of IgG/IgM had a sensitivity of 30.1% (95% CI 21.4 to 40.7) for 1 to 7 days, 72.2% (95% CI 63.5 to 79.5) for 8 to 14 days, 91.4% (95% CI 87.0 to 94.4) for 15 to 21 days. Estimates of accuracy beyond three weeks are based on smaller sample sizes and fewer studies. For 21 to 35 days, pooled sensitivities for IgG/IgM were 96.0% (95% CI 90.6 to 98.3). There are insufficient studies to estimate sensitivity of tests beyond 35 days post‐symptom onset. Summary specificities (provided in 35 studies) exceeded 98% for all target antibodies with confidence intervals no more than 2 percentage points wide. False‐positive results were more common where COVID‐19 had been suspected and ruled out, but numbers were small and the difference was within the range expected by chance.

Assuming a prevalence of 50%, a value considered possible in healthcare workers who have suffered respiratory symptoms, we would anticipate that 43 (28 to 65) would be missed and 7 (3 to 14) would be falsely positive in 1000 people undergoing IgG/IgM testing at days 15 to 21 post‐symptom onset. At a prevalence of 20%, a likely value in surveys in high‐risk settings, 17 (11 to 26) would be missed per 1000 people tested and 10 (5 to 22) would be falsely positive. At a lower prevalence of 5%, a likely value in national surveys, 4 (3 to 7) would be missed per 1000 tested, and 12 (6 to 27) would be falsely positive.

Analyses showed small differences in sensitivity between assay type, but methodological concerns and sparse data prevent comparisons between test brands.

Authors' conclusions

The sensitivity of antibody tests is too low in the first week since symptom onset to have a primary role for the diagnosis of COVID‐19, but they may still have a role complementing other testing in individuals presenting later, when RT‐PCR tests are negative, or are not done. Antibody tests are likely to have a useful role for detecting previous SARS‐CoV‐2 infection if used 15 or more days after the onset of symptoms. However, the duration of antibody rises is currently unknown, and we found very little data beyond 35 days post‐symptom onset. We are therefore uncertain about the utility of these tests for seroprevalence surveys for public health management purposes. Concerns about high risk of bias and applicability make it likely that the accuracy of tests when used in clinical care will be lower than reported in the included studies. Sensitivity has mainly been evaluated in hospitalised patients, so it is unclear whether the tests are able to detect lower antibody levels likely seen with milder and asymptomatic COVID‐19 disease.

The design, execution and reporting of studies of the accuracy of COVID‐19 tests requires considerable improvement. Studies must report data on sensitivity disaggregated by time since onset of symptoms. COVID‐19‐positive cases who are RT‐PCR‐negative should be included as well as those confirmed RT‐PCR, in accordance with the World Health Organization (WHO) and China National Health Commission of the People's Republic of China (CDC) case definitions. We were only able to obtain data from a small proportion of available tests, and action is needed to ensure that all results of test evaluations are available in the public domain to prevent selective reporting. This is a fast‐moving field and we plan ongoing updates of this living systematic review.

Plain language summary

What is the diagnostic accuracy of antibody tests for the detection of infection with the COVID‐19 virus?

Background

COVID‐19 is an infectious disease caused by the SARS‐CoV‐2 virus that spreads easily between people in a similar way to the common cold or ‘flu. Most people with COVID‐19 have a mild to moderate respiratory illness, and some may have no symptoms (asymptomatic infection). Others experience severe symptoms and need specialist treatment and intensive care.

The immune system of people who have COVID‐19 responds to infection by developing proteins that can attack the virus (antibodies) in their blood. Tests to detect antibodies in peoples' blood might show whether they currently have COVID‐19 or have had it previously.

Why are accurate tests important?

Accurate testing allows identification of people who might need treatment, or who need to isolate themselves to prevent the spread of infection. Failure to detect people with COVID‐19 when it is present (a false negative result) may delay treatment and risk further spread of infection to others. Incorrect identification of COVID‐19 when it is not present (a false positive result) may lead to unnecessary further testing, treatment, and isolation of the person and close contacts. Correct identification of people who have previously had COVID‐19 is important in measuring disease spread, assessing the success of public health interventions (like isolation), and potentially in identifying individuals with immunity (should antibodies in the future be shown to indicate immunity).

To identify false negative and false positive results, antibody test results are compared in people known to have COVID‐19 and known not to have COVID‐19. Study participants are classified as to whether they are known or not known to have COVID‐19 based on criteria known as the ‘reference standard’. Many studies use samples taken from the nose and throat to identify people with COVID‐19. The samples undergo a test called reverse transcriptase polymerase chain reaction (RT‐PCR). This testing process can sometimes miss infection (false negative result), but additional tests can identify COVID‐19 infection in people with a negative RT‐PCR result. These include measuring clinical symptoms, like coughing or high temperature, or ‘imaging’ tests like chest X‐rays. People known not to have COVID‐19 are sometimes identified from stored blood samples taken before COVID‐19 existed, or from patients with respiratory symptoms found to be caused by other diseases.

What did the review study?

The studies looked at three types of antibody, IgA, IgG and IgM. Most tests measure both IgG and IgM, but some measure a single antibody or combinations of the three antibodies.

Levels of antibodies rise and fall at different times after infection. IgG is the last to rise but lasts longest. Levels of antibodies are usually highest a few weeks after infection.

Some antibody tests need specialist laboratory equipment. Others use disposable devices, similar to pregnancy tests. These tests can be used in laboratories or wherever the patient is (point‐of‐care), in hospital or at home.

We wanted to find out whether antibody tests:

‐ are accurate enough to diagnose infection in people with or without symptoms of COVID‐19, and

‐ can be used to find out if someone has already had COVID‐19.

What did we do?

We looked for studies that measured the accuracy of antibody tests compared with reference standard criteria to detect current or past COVID‐19 infection. Studies could assess any antibody test compared with any reference standard. People could be tested in hospital or the community. Studies could test people known to have – or not to have – or be suspected of having COVID‐19.

Study characteristics

We found 54 relevant studies. Studies took place in Asia (38), Europe (15), and in both USA and China (1).

Forty‐six studies included people who were in hospital with suspected or confirmed COVID‐19 infection only. Twenty‐nine studies compared test results in people with COVID‐19 with test results in healthy people or people with other diseases.

Not all studies provided details about participants’ age and gender. Often, we could not tell whether studies were evaluating current or past infection, as few reported whether participants were recovering. We did not find any studies that tested only asymptomatic people.

Main results

Our findings come mainly from 38 studies that provided results based on the time since people first noticed symptoms.

Antibody tests one week after first symptoms only detected 30% of people who had COVID‐19. Accuracy increased in week 2 with 70% detected, and was highest in week 3 (more than 90% detected). Little evidence was available after week 3. Tests gave false positive results in 2% of those without COVID‐19.

Results from IgG/IgM tests three weeks after symptoms started suggested that if 1000 people had antibody tests, and 50 (5%) of them really had COVID‐19 (as we might expect in a national screening survey):

‐ 58 people would test positive for COVID‐19. Of these, 12 people (21%) would not have COVID‐19 (false positive result).

‐ 942 people would test negative for COVID‐19. Of these, 4 people (0.4%) would actually have COVID‐19 (false negative result).

If we tested 1000 healthcare workers (in a high‐risk setting) who had had symptoms, and 500 (50%) of them really had COVID‐19:

‐ 464 people would test positive for COVID‐19. Of these, 7 people (2%) would not have COVID‐19 (false positive result).

‐ 537 people would test negative for COVID‐19. Of these, 43 (8%) would actually have COVID‐19 (false negative result).

We did not find convincing differences in accuracy for different types of antibody test.

How reliable were the results of the studies of this review?

Our confidence in the evidence is limited for several reasons. In general, studies were small, did not use the most reliable methods and did not report their results fully. Often, they did not include patients with COVID‐19 who may have had a false negative result on PCR, and took their data for people without COVID‐19 from records of tests done before COVID‐19 arose. This may have affected test accuracy, but it is impossible to identify by how much.

Who do the results of this review apply to?

Most participants were in hospital with COVID‐19, so were likely to have more severe disease than people with mild symptoms who were not hospitalised. This means that we don't know how accurate antibody tests are for people with milder disease or no symptoms.

More than half of the studies assessed tests they had developed themselves, most of which are not available to buy. Many studies were published quickly online as ‘preprints’. Preprints do not undergo the normal rigorous checks of published studies, so we are not certain how reliable they are.

As most studies took place in Asia, we don't know whether test results would be similar elsewhere in the world.

What are the implications of this review?

The review shows that antibody tests could have a useful role in detecting if someone has had COVID‐19, but the timing of when the tests are used is important. Antibody tests may help to confirm COVID‐19 infection in people who have had symptoms for more than two weeks and do not have a RT‐PCR test, or have negative RT‐PCR test results. The tests are better at detecting COVID‐19 in people two or more weeks after their symptoms started, but we do not know how well they work more than five weeks after symptoms started. We do not know how well the tests work for people who have milder disease or no symptoms, because the studies in the review were mainly done in people who were in hospital. In time, we will learn whether having previously had COVID‐19 provides individuals with immunity to future infection.

Further research is needed into the use of antibody tests in people recovering from COVID‐19 infection, and in people who have experienced mild symptoms or who never experienced symptoms.

How up‐to‐date is this review?

This review includes evidence published up to 27 April 2020. Because a lot of new research is being published in this field, we will update this review frequently.

Summary of findings

Summary of findings 1. What is the diagnostic accuracy of antibody tests, for the diagnosis of current or prior SARS‐CoV‐2 infection?

Question	What is the diagnostic accuracy of antibody tests, for the diagnosis of current or prior SARS‐CoV‐2 infection?
Population	Adults or children suspected of current SARS‐CoV‐2 infection prior SARS‐CoV‐2 infection or populations undergoing screening for SARS‐CoV‐2 infection, including asymptomatic contacts of confirmed COVID‐19 cases community screening
Index test	Any test for detecting antibodies to SARS‐CoV‐2, including: laboratory‐based methods ELISA CLIA other laboratory‐based methods rapid tests; lateral flow assays, including tests that can be used at point‐of‐care, such as CGIA rapid diagnostic tests, such as FIA
Target condition	Detection of current SARS‐CoV‐2 infection prior SARS‐CoV‐2 infection
Reference standard	RT‐PCR alone, clinical diagnosis of COVID‐19 based on established guidelines or combinations of clinical features and for non‐COVID‐19 cases, the use of pre‐pandemic sources of samples for testing
Action	The current evidence‐base for antibody tests is inadequate to be clear about their utility (mainly because of small numbers of small studies for each test, few data available outside of acute hospital settings, and many issues in likely bias and applicability of the studies). The sensitivity of antibody tests is too low early in disease for use as a primary test of diagnosis, but they may have value for late diagnosis, for identifying previous infection, and for sero‐prevalence studies.
Limitations in the evidence
Risk of bias	Participant selection: high risk of bias in 48 studies (89%) Application of index tests: high risk of bias in 14 studies (26%) Reference standard: high risk of bias in 17 studies (31%) Flow and timing: high risk of bias in 29 studies (54%)
Concerns about applicability of the evidence	Participants: high concerns in 44 studies (81%) Index test: high concerns in 17 studies (31%) Reference standard: high concerns in 33 studies (61%)
Findings
We included 54 studies evaluating 15,976 samples. 8256 samples were from COVID‐19 cases. Data were not available for most antibody tests that have regulatory approval. Most studies reported on detection of IgG, IgM, or IgG/IgM antibodies. Test sensitivity was strongly related to time since onset of symptoms, with low sensitivity between 1 and 14 days, and sensitivity for IgG/IgM tests exceeding 90% between 15 and 35 days. Little evidence was available beyond 35 days. Specificity was high (> 98%) for all types of antibody. There was some variation in sensitivity between test methods, with laboratory‐based methods appearing to outperform (point‐of‐care) tests using disposable devices. Small sample sizes, low numbers of studies and concerns and bias and applicability hinder trustworthy comparisons being made between test brands.
Quantity of evidence	Number of studies	Total participants or samples		Total cases
	54	15,976		8526
	Sensitivity (95% CI) *Studies (TP/COVID cases)*			Specificity (95%CI) *Studies (FP/non‐COVID cases)*
	Days 8‐14	Days 15‐21	Days 22‐35	All time points
IgG	66.5% (57.9 to 74.2)	88.2% (83.5 to 91.8)	80.3% (72.4 to 86.4)	99.1% (98.3% to 99.6%)
	22 (766/1200)	22 (974/1110)	12 (417/502)	44 (159/6136)
IgM	58.4% (45.5 to 70.3)	75.4% (64.3 to 83.8)	68.1% (55.0 to 78.9)	98.7% (97.4% to 99.3%)
	21 (724/1171)	21 (800/1074)	11 (378/507)	41 (183/6103)
IgG/IgM*	72.2% (63.5 to 79.5)	91.4% (87.0 to 94.4)	96.0% (90.6 to 98.3)	98.7% (97.2% to 99.4%)
	9 (441/608)	9 (636/692)	5 (146/152)	23 (78/5761)
Numbers applied to a hypothetical cohort of 1000 patients, using summary data for IgG/IgM at days 15 to 21 as an exemplar (sensitivity 91.4% (87.0 to 94.4) and specificity 98.7% (97.2 to 99.4))
Prevalence of COVID‐19	TP (95% CI)	FP (95% CI)	FN (95% CI)	TN (95% CI)
2%	18 (17 to 20)	13 (6 to 27)	2 (1 to 3)	967 (953 to 974)
5%	46 (44 to 47)	12 (6 to 27)	4 (3 to 7)	938 (923 to 944)
10%	91 (87 to 94)	12 (5 to 25)	9 (6 to 13)	888 (875 to 895)
20%	183 (174 to 189)	10 (5 to 22)	17 (11 to 26)	790 (778 to 795)
50%	457 (435 to 472)	7 (3 to 14)	43 (28 to 65)	494 (486 to 497)
CGIA: colloidal gold immunoassays; CI: confidence interval; CLIA: chemiluminescence immunoassays; ELISA: enzyme‐linked immunosorbent assays; FIA: fluorescence‐labelled immunochromatographic assays; FN: false negative; FP: false positive; RT‐PCR: reverse transcription polymerase chain reaction; TN: true negative; TP: true positive; * Positive if either IgG or IgM positive.

Participants		Studies (percentage) (n=54 studies)
Sample size	Median (IQR) 129.5 (57 to 347)	Min 10, max 3481
Number of COVID‐19 cases	Median (IQR) 62 (31 to 151)	Min 3, max 555
Setting	Hospital inpatient	44 (81%)
	Hospital outpatient	1 (2%)
	Hospital accident and emergency	2 (4%)
	Community	2 (4%)
	Mixed or unclear	5 (9%)
Patient group	Asymptomatic	0 (0%)
	Asymptomatic and acute	1 (2%)
	Acute	23 (43%)
	Acute and convalescent	22 (41%)
	Convalescent	2 (4%)
	Mixed or unclear	6 (11%)
Study design
Recruitment structure	Single group, both COVID‐19 and non‐COVID‐19 cases	6 (11%)
	Single group, only COVID‐19 cases	19 (35%)
	Two or more groups with COVID‐19 and non‐COVID‐19 cases	29 (54%)
Reference standard for COVID‐19 cases	All RT‐PCR‐positive	32 (59%)
	China CDC criteria including RT‐PCR‐negative patients	11 (20%)
	WHO criteria including RT‐PCR‐negative patients	1 (2%)
	Other criteria including RT‐PCR‐negative patients	3 (6%)
	Other	2 (4%)
	Mixed or unclear	5 (9%)
Reference standard for non‐COVID‐19	Pre‐pandemic healthy	4 (7%)
	Pre‐pandemic other disease	3 (6%)
	Pre‐pandemic healthy + other disease	4 (7%)
	Current healthy (untested)	5 (9%)
	Current other disease (untested)	1 (2%)
	Current healthy + other disease (untested)	2 (4%)
	Current healthy + other disease (RT‐PCR‐negative)	2 (4%)
	COVID suspects, single RT‐PCR‐negative	8 (15%)
	COVID suspects, two or more RT‐PCR–negative results	3 (6%)
	Mixed/other	3 (6%)
Tests
Number of tests per study	1	40 (74%)
	2	8 (15%)
	3‐5	4 (8%)
	6‐10	2 (2%)
Test technology (n = 89)	CGIA	23 (26%)
	CLIA	20 (22%)
	ELISA	28 (31%)
	FIA	2 (2%)
	IIFT	1 (1%)
	LFA (no details)	10 (11%)
	LIPS	4 (4%)
	S‐flow	1 (1%)
Test brand (n = 89)	Withheld	13 (%)
	Acro Biotech ‐ IgG/IgM	1 (1%)
	Artron Laboratories IgM/IgG	1 (1%)
	Autobio Diagnostics IgM/IgG	1 (1%)
	Beijing Beier Bioengineering CGIA	1 (1%)
	Beijing Beier Bioengineering CLIA	1 (1%)
	Beijing Beier Bioengineering ELISA	1 (1%)
	Beijing Diagreat	1 (1%)
	Beijing Hotgen CGIA	1 (1%)
	Beijing Hotgen ELISA	2 (3%)
	Beijing Wantai CGIA	1 (1%)
	Beijing Wantai ELISA	3 (3%)
	Bioscience Co (Chongqing)	3 (3%)
	CTK Biotech OnSite IgG/IgM	1 (1%)
	Darui Biotech	1 (1%)
	Dynamiker Biotechnology IgG/IgM	1 (1%)
	EUROIMMUN	3 (3%)
	EUROIMMUN Anti‐SARS‐Cov	1 (1%)
	EUROIMMUN Beta	1 (1%)
	Hangzhou Alltest ‐ IgG/IgM	3 (3%)
	Innovita Biological ‐ Ab test (IgM/IgG)	2 (3%)
	Jiangsu Medomics IgG‐IgM	1 (1%)
	Shenzhen YHLO	7 (8%)
	Snibe Diagnostic ‐ MAGLUMI	2 (3%)
	Vivachek ‐ VivaDiag IgM/IgG	3 (3%)
	Xiamen InnodDx Biotech	1 (1%)
	Zhuhai Livzon CGIA	2 (3%)
	Zhuhai Livzon ELISA	5 (6%)
	In‐house, S‐based ELISA	1 (1%)
	In‐house, S‐based LIPS	1 (1%)
	In‐house, rN‐based ELISA	1 (1%)
	In‐house, rS‐based ELISA	1 (1%)
	In‐house CGIA	2 (2%)
	In‐house CLIA	5 (6%)
	In‐house ELISA	6 (7%)
	In‐house FIA	1 (1%)
	In‐house S‐flow	1 (1%)
	In‐house ‐ N‐based ELISA	1 (1%)
	In‐house ‐ N‐based LIPS	2 (2%)
	In‐house ‐ S1‐based LIPS	1 (1%)
	In‐house ‐ tri‐S‐based ELISA	1 (1%)
	In‐house Anti‐SARS‐Cov ELISA	1 (1%)
Ab: antibody; CDC: Center for Disease Control and Prevention; CGIA: colloidal gold immunoassay; CLIA: chemiluminescence immunoassay; ELISA: enzyme‐linked immunosorbent assay; FIA: fluorescence immunoassay; IQR: interquartile range; IIFT: indirect immunofluorescence assay; LFA: lateral flow assay; LIPS: luciferase immunoprecipitation system; max: maximum; min: minimum; N‐based: nucleocapsid protein; RT‐PCR: reverse transcription polymerase chain reaction; S‐based: spike protein; S‐flow: flow‐cytometry assay; WHO: World Health Organization

	Days 1‐7	Days 8‐14	Days 15‐21	Days 22‐35	Days > 35	Comparison
	Test groups [studies] (true positives/COVID cases) Sensitivity (95% CI)
IgG	33 [23] (165/568)	34 [22] (766/1200)	34 [22] (974/1110)	20 [12] (417/502)	11 [4] (213/252)
	29.7% (22.1 to 38.6)	66.5% (57.9 to 74.2)	88.2% (83.5 to 91.8)	80.3% (72.4 to 86.4)	86.7% (79.6 to 91.7)	P < 0.00005
IgM	34 [24] (207/608)	32 [21] (724/1171)	32 [21] (800/1074)	19 [11] (378/507)	11 [4] 118/215
	23.2% (14.9 to 34.2)	58.4% (45.5 to 70.3)	75.4% (64.3 to 83.8)	68.1% (55.0 to 78.9)	53.9% (38.4 to 68.6)	P < 0.00005
IgA	4 [4] (54/100)	3 [3] (38/53)	3 [3] (66/68)	2 [2] (81/82)	1 [1] (23/23)
	28.4% (0.9 to 94.3)	78.1% (9.5 to 99.2)	98.7% (39.0 to 100)	98.7% (91.9 to 99.8)	100% (85.2 to 100)	*
Total antibodies	5 [4] (62/144)	6 [5] (220/247)	6 [5] (174/176)	4 [3] (11/19)	2 [1] (15/28)
	24.5% (9.5 to 50.0)	84.0% (64.1 to 93.9)	98.1% (90.1 to 99.6)	69.5% (34.8 to 90.7)	79.0% (49.8 to 93.4)	P < 0.00005
IgG/IgM	17 [9] (81/259)	21 [9] (441/608)	21 [9] (636/692)	16 [5] (146/152)	9 [2] (122/153)
	30.1% (21.4 to 40.7)	72.2% (63.5 to 79.5)	91.4% (87.0 to 94.4)	96.0% (90.6 to 98.3)	77.7% (66.0 to 86.2)	P < 0.00005
IgA/IgG	1 [1] (0/12)	1 [1] (5/10)	1 [1] (7/8)	1 [1] (1/1)	0 [0]
	0% (0 to 26.5)	50.0% (18.7 to 81.3)	87.5% (47.3 to 99.6)	100% (2.5 to 100)		*
IgA/IgM	0 [0]	0 [0]	0 [0]	0 [0]	0 [0]
CI: confidence interval; * inadequate data to make a formal statistical comparison

	Overall specificity^a	COVID suspects deemed negative	Current healthy or other disease	Pre‐pandemic	Comparison of control groups
	Test groups [studies] (false positives/non‐COVID cases) Specificity (95% CI)
IgG	62 [44] (159/6136)	6 [6] (10/396)	14 [10] (60/2614)	19 [10] (88/2633)
	99.1% (98.3% to 99.6%)	98.0% (91.0% to 99.6%)	99.2% (97.6% to 99.8%)	99.2% (97.8% to 99.7%)	P = 0.56
IgM	59 [41] (183/6103)	5 [5] (12/384)	14 [10] (89/3069)	17 [9] (38/2075)
	98.7% (97.4% to 99.3%)	98.1% (89.9% to 99.7%)	98.6% (96.0% to 99.5%)	99.3% (98.0% to 99.8%)	P = 0.50
IgG/IgM	34 [23] (78/5761)	7 [7] (33/454)	7 [5] (20/506)	18 [6] (22/1104)	No formal comparison possible
	98.7% (97.2% to 99.4%)	92.8% (89.7% to 95.0%)	99.9% (65.2% to 100%)	98.7% (96.6% to 99.5%)
Total antibodies	16 [10] (41/3585)
	99.2% (98.3% to 99.6%)
IgA	4 [4] (10/663)
	98.5% (97.2% to 99.2%)
IgA/IgG^b	2 [2] (1/528)
	99.8% (98.9% to 100%)
IgA/IgM^b	1 [1] (1/483)
	99.8% (99.2% to 100%)
CI: confidence interval

Study	Test(s) evaluated	What the study says about cross‐reactivity
Cai 2020	In‐house CLIA	Reported no cross‐reactivity in 167 sera from patients with infection with other pathogens (influenza A virus (25), respiratory syncytial virus (7), parainfluenza virus (8), influenza B virus (5), adenovirus (6), Klebsiella pneumoniae (8), Streptococcus pneumoniae (3), mycoplasma (5), Acinetobacter baumannii (10), Candida albicans (2), Staphylococcus aureus (3), Mycobacterium tuberculosis (4), hepatitis B virus (33), hepatitis C virus (22), syphilis (23) and saccharomycopsis (3)).
Freeman 2020	In‐house ELISA	Reported cross‐reactivity to SARS‐CoV‐2 spike protein in sera from patients with SARS‐1 and MERS‐CoV, and no cross‐reactivity with NL63, OC43, HKU1, 229E
Guo 2020a	In‐house ELISA	Reported Western Blot cross‐reactivity analysis in plasma samples positive for human CoV‐229E, ‐NL63, ‐OC43, ‐HKU1, and SARS‐CoV. Strong cross‐reactivity was observed only for SARS‐CoV.
Infantino 2020	Shenzhen YHLO CLIA	Observed no cross‐reactivity in sample from blood donors from the COVID‐19 era (winter 2019) but positive results in two samples from people with CMV infections and 2 with rheumatic disease.
Lassauniere 2020 [A]	[A] Beijing Wantai ELISA [B] EUROIMMUN IgG ELISA [C] EUROIMMUN IgA ELISA [D] Dynamiker Biotechnology LFA [E] CTK Biotech ‐ OnSite LFA [F] Autobio Diagnostics LFA [G] Artron Laboratories LFA [H] Acro Biotech LFA [I] Hangzhou Alltest LFA	Included sera from patients with acute viral respiratory tract infections caused by other coronaviruses (n = 5) or non‐coronaviruses (n = 45), and sera from patients positive for dengue virus (n = 9), CMV (n = 2) and Epstein Barr virus (n = 10). Cross reaction was observed for the EUROMIMMUN IgA ELISA (> 1 respiratory virus present, adenovirus, dengue virus) and for the EUROMIMMUN IgG ELISA (coronavirus HKU1 and adenovirus). Some cross‐reactivity also observed for CGIA tests. Study authors suggest related to antigen target and ELISA format.
Ma 2020a	In‐house CLIA	Limited detail but suggests limited cross‐reaction
Wang 2020a [A]	A. Beijing Hotgen IgM CGIA B. Beijing Hotgen IgM ELISA	Demonstrated considerable cross‐reaction with rheumatoid factor IgM (22/36 false positive results). Other pathogens included influenza A virus (n = 5), influenza B virus (n = 5), Mycoplasma pneumoniae (n = 5), Legionella pneumophila (n = 5), HIV infection (n = 6), hypertension (n = 5) and diabetes mellitus (n = 5)
Zhang 2020b	Shenzhen YHLO CLIA	Observed false positive results in influenza A and B (2 each), adenovirus (n = 4) and Mycoplasma pneumoniae (n = 17).
Zhang 2020d	In‐house CGIA (co‐author Beijing Hotgen)	Appears to report a separate cross‐reactivity study for influenza A, influenza B, respiratory syncytial virus, Mycoplasma pneumoniae and Chlamydia pneumoniae. No cross reactions were observed.
CGIA: colloidal gold immunoassay; CLIA: Chemiluminescence immunoassay; CMV: cytomegalovirus; ELISA: enzyme‐linked immunosorbent assay; LFA: lateral flow assay; MERS: Middle East respiratory syndrome; SARS: severe acute respiratory syndrome

	RT‐PCR‐positive COVID‐19 cases	RT‐PCR‐negative COVID‐19 cases	Comparison
	Test groups [studies] (true positives/COVID cases) Sensitivity (95% CI)^a
IgG	26 [15] (1555/2280)	8 [8] (925/1300)
	87.9% (82.7 to 91.7)	91.2% (83.9 to 95.4)	P = 0.36
IgM	23 [13] (1368/2166)	10 [9] (792/1292)
	70.8% (56.3 to 82.0)	87.5% (73.7 to 94.6)	P = 0.06
IgG/IgM	17 [6] (966/1278)	4 [4] (400/499)
	90.6% (86.6 to 93.5)	93.6% (88.9 to 96.4)	P = 0.22
CI: confidence interval; RT‐PCR: reverse transcription polymerase chain reaction

	RT‐PCR‐positive COVID‐19 cases		RT‐PCR‐negative COVID‐19 cases
	Test groups [studies] (True positives/COVID‐19 cases)	Sensitivity (95% CI)	Test groups [studies] (True positives/COVID‐19 cases)	Sensitivity (95% CI)
IgG
Days 1‐7^b	2 [2] (1/28)		2 [2] (8/13)
Days 8‐14^b	2 [2] (21/33)		3 [3] (25/30)
Days 15‐21^b	2 [2] (39/40)		3 [3] (64/72)
Pooled^a (stratified by time)		72.6% (46.2% to 89.1%)		84.0% (64.4% to 93.9%)
Test for difference in sensitivity between RT‐PCR‐positive and RT‐PCR‐negative groups: P = 0.18
IgM
Days 1‐7^b	2 [2] (3/28)		2 [2] (4/13)
Days 8‐14^b	2 [2] (25/33)		3 [3] (11/30)
Days 15‐21^b	2 [2] (8/16)		3 [3] (31/72)
Pooled^a (stratified by time)		64.6% (49.7% to 77.1%)		49.0% (34.2% to 63.9%)
Test for difference in sensitivity between RT‐PCR‐positive and RT‐PCR‐negative group: P = 0.07
IgG/IgM
Days 1‐7^b	2 [2] (8/36)		2 [2] (4/17)
Days 8‐14^b	2 [2] (37/53)		3 [3] (29/40)
Days 15‐21^b	2 [2] (141/150)		3 [3] (104/113)
Pooled^a (stratified by time)		71.9% (58.7% to 82.2%)		71.1% (57.0% to 82.0%)
Test for difference in sensitivity between RT‐PCR‐positive and RT‐PCR‐negative group: P = 0.90
CI: confidence interval; RT‐PCR: reverse transcription polymerase chain reaction

		Test method
	Test method	CGIA	CLIA	ELISA	LFA	Comparison
IgG
	Test groups [studies] (True positives/COVID cases)	6 [5] (268/397)	10 [10] (1112/1432)	12 [11] (1014/1552)	7 [1] (133/238)
	Sensitivity (95% CI)^a	87.3% (77.0 to 93.4)	94.6% (90.7 to 97.0)	85.8% (78.0 to 91.1)	76.0% (61.0 to 86.5)	P = 0.004
	Test groups [studies] (True negatives/non‐COVID cases)	11 [11] (409/415)	12 [12] (318/322)	18 [16] (2003/2102)	6 [1] (354/360)
	Specificity (95% CI)^a	99.5% (96.5 to 99.9)	99.0% (91.6 to 99.9)	98.8% (96.5 to 99.6)	99.0% (95.3 to 99.8)	P = 0.85
IgM
	Test groups [studies] (True positives/COVID cases)	7 [6] (109/411)	10 [10] (884/1355)	12 [11] (1083/1568)	7 [1] (78/228)
	Sensitivity (95% CI)^a	69.5% (44.3 to 86.7)	80.9% (63.8 to 91.0)	84.5% (70.7 to 92.5)	51.4% (26.5 to 75.6)	P = 0.11
	Test groups [studies] (True negatives/non‐COVID cases)	12 [11] (455/487)	13 [13] (609/621)	14 [12] (1674/1710)	6 [1] (357/360)
	Specificity (95% CI)^a	97.3 (90.0 to 99.3)	98.5 (92.3 to 99.7)	99.1 (97.2 to 99.7)	99.6 (97.3 to 99.9)	P = 0.40
IgG/IgM
	Test groups [studies] (True positives/COVID cases)	4 [3] (232/316)	3 [3] (344/420)	5 [4] (595/770)	11 [2] (255/358)
	Sensitivity (95% CI)^a	90.7% (82.7 to 95.2)	97.5% (94.0 to 99.0)	90.7% (83.3 to 95.0)	88.6% (82.0 to 93.0)	P = 0.02
	Test groups [studies] (True negatives/non‐COVID cases)	11 [11] (330/353)	5 [4] (230/244)	5 [4] (387/391)	13 [3] (3797/3827)
	Specificity (95% CI)^a	96.0 (90.1 to 98.5)	94.1 (82.7 to 98.2)	99.4 (97.4 to 99.9)	98.2 (96.3 to 99.1)	P = 0.05
CGIA: colloidal gold immunoassay; CI: confidence interval; CLIA: chemiluminescence immunoassay; ELISA: enzyme‐linked immunosorbent assay; LFA: lateral flow assay (no further detail)

Test name^a	Test method	IgG sensitivity by time since onset of symptoms Studies (true positives/COVID‐19 cases) Sensitivity (95% CI)					IgG specificity Studies (false positives/COVID‐19 cases) Specificity (95% CI)
		1‐7 days	8‐14 days	15‐21 days	22‐35 days	> 35 days
Beijing Beier Bioengineering	CGIA	1 (2/10)	1 (6/13)	1 (11/14)
		20.0% (2.5 to 55.6)	46.2% (19.2 to 74.9)	78.6% (49.2 to 95.3)
Beijing Beier Bioengineering	CLIA	1 (4/10)	1 (6/13)	1 (9/14)
		40.0% (12.2 to 73.8)	46.2% (19.2 to 74.9)	64.3% (35.1 to 87.2)
Beijing Beier Bioengineering	ELISA	1 (4/10)	1 (8/13)	1 (12/14)
		40.0% (12.2 to 73.8)	61.5% (31.6 to 86.1)	85.7% (57.2 to 98.2)
Beijing Hotgen	ELISA	1 (9/22)	1 (60/92)	1 (51/55)	1 (39/45)		2 (22/172)
		40.9% (20.7 to 63.6)	65.2% (54.6 to 74.9)	92.7% (82.4 to 98.0)	86.7% (73.2 to 94.9)		87.2% (81.3 to 91.8)
Beijing Wantai	ELISA	2 (31/133)	2 (130/210)	2 (127/149)			2 (2/297)
		23.3% (16.4 to 31.4)	61.9% (55.0 to 68.5)	85.2% (78.5 to 90.5)			99.3% (97.6 to 99.9)
Beijing Wantai	CGIA						1 (1/209)
							99.5% (97.4 to 100)
Bioscience Co (Chongqing)	CLIA	2 (43/92)	2 (129/212)	2 (208/244)	2 (98/164)	1 (75/76)
		46.7% (36.3 to 57.4)	60.8% (53.9 to 67.5)	85.2% ( 80.2 to 89.4)	59.8% (51.8 to 67.3)	98.6% (92.9 to 100)
Darui Biotech	ELISA						1 (0/64)
							100% (94.4 to 100)
EUROIMMUN	ELISA	1 (2/13)	2 (13/25)	2 (14/15)	2 (98/164)		2 (3/82)
		15.4% (1.9 to 45.4)	52.0% (31.3 to 72.2)	93.3% (68.1 to 99.8)	59.8% (51.8 to 67.3)		96.3% (89.7 to 99.2)
EUROIMMUN Anti‐SARS‐Cov	IIFT	1 (1/4)	1 (3/5)	1 (3/3)	1 (1/1)		1 (0/10)
		25.0% (0.6 to 80.6)	60.0% (14.7 to 94.7)	100% (29.2 to 100)	100% (2.5 to 100)		100% (69.2 to 100)
EUROIMMUN Beta	ELISA	1 (0/12)	1 (3/10)	1 (7/8)	1 (1/1)		1 (0/45)
		0% (0 to 26.5)	30%.0% (14.7 to 94.7)	87.5% (47.3 to 99.7)	100% (2.5 to 100)		100% (92.1 to 100)
Hangzhou Alltest ‐ IgG/IgM	CGIA	1 (1/8)	2 (21/42)	2 (57/68)			2 (0/45)
		12.5% (0.3 to 52.7)	50.0% (34.2 to 65.8)	83.8% (72.9 to 91.6)			100% (92.1 to 100)
Innovita Biological ‐ Ab test (IgM/IgG)	CGIA	1 (7/13)	1 (7/8)	1 (21/23)
		53.8% (25.1 to 80.8)	87.5% (47.3 to 99.7)	91.3% (72.0 to 98.9)
Shenzhen YHLO	CLIA	2 (2/8)	2 (28/29)	2 (25/26)	2 (64/64)	1 (7/7)	7 (4/322)
		25.0% (3.2 to 65.1)	96.6% (82.2 to 99.9)	96.2% (80.4 to 99.9)	100% (94.4 to 100)	100% (59.0 to 100)	98.8% (96.9 to 99.7)
Snibe Diagnostic ‐ MAGLUMI	CLIA	2 (11/40)	2 (35/48)	25/25
		27.5% (14.6 to 43.9)	72.9% (58.2 to 84.7)	100.0% (86.3 to 100)
Vivachek ‐ VivaDiag IgM/IgG	CGIA						2 (0/42)
							100% (91.6 to 100)
Zhuhai Livzon	CGIA	1 (5/36)	1 (20/34)	1 (35/38)			2 (0/35)
		13.9% (4.7 to 29.5)	58.8% (40.7 to 75.4)	92.1% (78.6 to 98.3)			100% ( 90.0 to 100)
Zhuhai Livzon	ELISA	4 (17/80)	3 (163/288)	3 (197/223)	2 (91/104)		5 (5/351)
		21.3% (12.9 to 31.8)	56.6% (50.7 to 62.4)	88.3% (83.4 to 92.2)	87.5% (79.6 to 93.2)		98.6% (96.7 to 99.5)
CGIA: colloidal gold immunoassay; CI: confidence interval; CLIA: chemiluminescence immunoassay; ELISA: enzyme‐linked immunosorbent assay; FIA: fluorescence immunoassay; IIFT: indirect immunofluorescence assay; LFA: lateral flow assay

Test name^a	Test method	IgM sensitivity by time since onset of symptoms Studies (true positives/COVID‐19 cases) Sensitiivity (95% CI)					IgM specificity Studies (false positives/COVID‐19 cases) Specificity (95% CI)
		1‐7 days	8‐14 days	15‐21 days	22‐35 days	> 35 days
Artron Laboratories IgM/IgG	CGIA		1 (5/7)	1 (12/15)	1 (8/8)
			71.4% (29.0 to 96.3)	80.0% (51.9 to 95.7)	100% (63.1 to 100)
Autobio Diagnostics IgM/IgG	CGIA		1 (6/7)	1 (14/15)	1(8/8)
			85.7% (42.1 to 99.6)	93.3% (68.1 to 99.8)	100% (63.1 to 100)
Beijing Hotgen	ELISA	1 (10/22)	1 (72/92)	1 (72/92)	1 (41/45)		1 (0/100)
		45.5% (24.4 to 67.8)	78.3% (68.4 to 86.2)	78.3% (68.4 to 86.2)	91.1% (78.8 to 97.5)		100% (96.4 to 100)
Beijing Hotgen	CGIA						1 (22/72)
							69.4% (57.5 to 79.8)
Beijing Wantai	ELISA						1 (3/513)
							99.4% (98.3 to 99.9)
Beijing Wantai	CGIA						1 (4/209)
							98.1% (95.2 to 99.5)
Bioscience Co (Chongqing)	CLIA	1 (34/67)	1 (34/67)	1 (131/134)	1 (13/13)
		50.7% (38.2 to 63.2)	50.7% (38.2 to 63.2)	97.8% (93.6 to 99.5)	100% (75.3 to 100)
CTK Biotech OnSite IgG/IgM	CGIA		1 (5/7)	1 (14/15)	1 (8/8)
			71.4% (29.0 to 96.3)	93.3% (68.1 to 99.8)	100% (63.1 to 100)
Darui Biotech	ELISA						1 (14/64)
							78.1% (66.0 to 87.5)
Dynamiker Biotechnology IgG/IgM	CGIA		1 (5/7)	1 (14/15)	1 (8/8)
			71.4% (29.0 to 96.3)	93.3% (68.1 to 99.8)	100% (63.1 to 100)
EUROIMMUN	ELISA						1 (76/82)
							92.7% (84.8 to 97.3)
EUROIMMUN Anti‐SARS‐Cov	IIFT						1 (1/10)
							90.0% (55.5 to 99.7)
Hangzhou Alltest ‐ IgG/IgM	CGIA	1 (1/8)	2 (23/42)	2 (58/68)			2 (0/45)
		12.5% (0.3 to 52.7)	54.8% (38.7 to 70.2)	85.3% (74.6 to 92.7)			100% (92.1 to 100)
Shenzhen YHLO	CLIA						7 (10/321)
							96.9% (94.3 to 98.5)
Vivachek ‐ VivaDiag IgM/IgG	CGIA						2 (1/42)
							97.6% (87.4 to 99.9)
Xiamen InnodDx Biotech	CLIA						1 (2/300)
							99.3% (97.6 to 99.9)
Zhuhai Livzon	CGIA	1 (7/36)	1 (31/34)	1 (35/38)			2 (0/35)
		19.4% (8.2 to 36.0)	91.2% (76.3 to 98.1)	92.1% (78.6 to 98.3)			100% ( 90.0 to 100)
Zhuhai Livzon	ELISA	3 (14/66)	2 (150/202)	2 (159/166)	1 (43/45)		5 (3/351)
		21.2% (12.1 to 33.0)	74.3% (67.7 to 80.1)	95.8% (91.5 to 98.3)	95.6% (84.9 to 99.5)		99.1% (97.5 to 99.8)
CGIA: colloidal gold immunoassay; CI: confidence interval; CLIA: chemiluminescence immunoassay; ELISA: enzyme‐linked immunosorbent assay; FIA: fluorescence immunoassay; IIFT: indirect immunofluorescence assay; LFA: lateral flow assay

Test name^a	Test method	IgG/IgM sensitivity by time since onset of symptoms Studies (true positives/COVID‐19 cases) Sensitiivity (95% CI)					IgG/IgM specificity Studies (false positives/COVID‐19 cases) Specificity (95% CI)
		1‐7 days	8‐14 days	15‐21 days	22‐35 days	> 35 days
Acro Biotech ‐ IgG/IgM	CGIA						1 (3/15)
							80.0% (51.9 to 95.7)
Artron Laboratories IgM/IgG	CGIA		1 (5/7)	1 (12/15)	1 (8/8)		1 (0/17)
			71.4% (29.0 to 96.3)	80.0% (51.9 to 95.7)	100% (63.1 to 100)		100% (80.5% to 100)
Autobio Diagnostics IgM/IgG	CGIA		1 (6/7)	1 (14/15)	1(8/8)		1 (0/32)
			85.7% (42.1 to 99.6)	93.3% (68.1 to 99.8)	100% (63.1 to 100)		100% (89.1 to 100)
Beijing Hotgen	ELISA	1 (10/22)	1 (72/92)	1 (72/92)	1 (41/45)		1 (0/100)
		45.5% (24.4 to 67.8)	78.3% (68.4 to 86.2)	78.3% (68.4 to 86.2)	91.1% (78.8 to 97.5)		100% (96.4 to 100)
Bioscience Co (Chongqing)	CLIA	1 (34/67)	1 (34/67)	1 (131/134)	1 (13/13)		2 (7/148)
		50.7% (38.2 to 63.2)	50.7% (38.2 to 63.2)	97.8% (93.6 to 99.5)	100% (75.3 to 100)		95.3% (90.5 to 98.1)
CTK Biotech OnSite IgG/IgM	CGIA		1 (5/7)	1 (14/15)	1 (8/8)		1 (0/32)
			71.4% (29.0 to 96.3)	93.3% (68.1 to 99.8)	100% (63.1 to 100)		100% (89.1 to 100)
Dynamiker Biotechnology IgG/IgM	CGIA		1 (5/7)	1 (14/15)	1 (8/8)		1 (0/32)
			71.4% (29.0 to 96.3)	93.3% (68.1 to 99.8)	100% (63.1 to 100)		100% (89.1 to 100)
Hangzhou Alltest ‐ IgG/IgM	CGIA	1 (1/8)	2 (23/42)	2 (58/68)			3 (2/60)
		12.5% (0.3 to 52.7)	54.8% (38.7 to 70.2)	85.3% (74.6 to 92.7)			96.7% (88.5 to 99.6)
Shenzhen YHLO	CLIA						2 (7/96)
							92.7% (85.6 to 97.0)
Vivachek ‐ VivaDiag IgM/IgG	CGIA						3 (14/162)
							91.4% (85.9 to 95.2)
Zhuhai Livzon	CGIA	1 (7/36)	1 (31/34)	1 (35/38)			2 (0/35)
		19.4% (8.2 to 36.0)	91.2% (76.3 to 98.1)	92.1% (78.6 to 98.3)			100% (90.0 to 100)
Zhuhai Livzon	ELISA	3 (14/66)	2 (150/202)	2 (159/166)	1 (43/45)		4 (4/291)
		21.2% (12.1 to 33.0)	74.3% (67.7 to 80.1)	95.8% (91.5 to 98.3)	95.6% (84.9 to 99.5)		98.6% (96.5 to 99.6)
CGIA: colloidal gold immunoassay; CI: confidence interval; CLIA: chemiluminescence immunoassay; ELISA: enzyme‐linked immunosorbent assay; FIA: fluorescence immunoassay; IIFT: indirect immunofluorescence assay; LFA: lateral flow assay

Dates in effect	Definition of confirmed case	Definition of confirmed non‐case	Definition of suspect case	Role of serology in testing
16‐17 January 2020 (version 1)	Cases (not confirmed cases) defined as virus genome highly homologous to coronaviruses	Not defined	Observation cases: defined as combination of exposure in Wuhan and symptoms focused on pneumonia, leukopenia and lack of improvement.	No role
18 January‐2 March (versions 2, 3, 4, 5, 5 revised, and 6)	Suspect cases with either real‐time fluorescent RT‐PCR indicates positive for new coronavirus nucleic acid; OR viral gene sequence is highly homologous to known new coronaviruses.	Suspect cases can be ruled out after 2 consecutive negative respiratory tract nucleic acid tests taken at least 24‐hours apart.	Suspect cases: combination of exposure (such as residence in/travel to Wuhan or exposure to a confirmed case within 14 days of onset) AND clinical features (such as symptoms: fever, respiratory symptoms, and tests: chest imaging, white blood cell and lymphocyte count). Exact definition varies slightly with version	No role
3 March‐present (version 7)	Suspect cases with either real‐time fluorescent RT‐PCR indicates positive for new coronavirus nucleic acid; OR viral gene sequence is highly homologous to known new coronaviruses. OR NCP virus‐specific IgM and IgG are detectable in serum; NCP virus‐specific IgG is detectable or reaches a titration of at least 4‐fold increase during convalescence compared with the acute phase.	Suspect cases can be ruled out after 2 negative NAATs, taken at least 24‐hours apart, and the NCP virus‐specific IgM and IgG are negative after 7 days from onset.	Suspect cases: combination of exposure (such as residence in/travel to Wuhan or exposure to a confirmed case within 14 days of onset) AND clinical features (such as symptoms: fever, respiratory symptoms, and tests: chest imaging, white blood cell and lymphocyte count).	Part of definition of cases and confirmed non‐cases
NAAT: nucleic acids amplification test; NCP: novel coronavirus pneumonia; RT‐PCR: reverse transcription polymerase chain reaction; Source: CDC China 2020.

Use Case^a	Advantages	Limitations		Considerations
Diagnosis
Aid diagnosis of suspect cases, especially when RT‐PCR negative but X‐Ray/CT suggestive	May improve overall sensitivity of diagnosis Diagnosis of patients presenting late or for post‐infectious syndromes (low viral load) Diagnosis of patients when lower respiratory tract sampling not available	Unlikely to catch early‐stage infection (< 7 days) May not detect asymptomatic cases Negative test cannot rule out infection IgM appears early, but is less specific	Total antibody may have best sensitivity Should be confirmed by PCR, where possible Rising titres and seroconversion can improve sensitivity and specificity
Aid diagnosis of suspect cases when PCR is not available (would require careful development of interpretive guidelines)	As above and could enable decentralised/community testing in settings where the availability of PCR testing is limited.
Identification of individuals with protective immune status  (conditional upon identifying correlates of protection for SARS‐CoV‐2)
Identify convalescent plasma donors	Treatment for critically ill patients	Ideal timing of collection unknown to optimise efficaciousness	Preferentially patients recovered from moderate to severe disease (high titre). Theoretically may be derived from vaccinated donors
CT: computed tomography; RT‐PCR: reverse transcription polymerase chain reaction;
^aTable from Cheng 2020b

Source	Strategy
CT.gov	COVID‐19^a
WHO ICTRP	Health topic: 2019‐nCov / COVID‐19
PubMed	(("2019 nCoV"[tiab] OR 2019nCoV[tiab] OR "2019 novel coronavirus"[tiab] OR "COVID 19"[tiab] OR COVID19[tiab] OR "new coronavirus"[tiab] OR "novel coronavirus"[tiab] OR "novel corona virus"[tiab] OR "SARS CoV‐2"[tiab] OR (Wuhan[tiab] AND (coronavirus[tiab] OR "corona virus"[tiab])) OR "COVID‐19"[Supplementary Concept] OR "severe acute respiratory syndrome coronavirus 2"[Supplementary Concept]) NOT ("animals"[MeSH Terms] NOT "humans"[MeSH Terms])) NOT (editorial[pt] OR comment[pt] OR letter[pt] OR newspaper article[pt])

Patient sampling items	Patient characteristics and setting items	Index test items	Reference standard items	Flow and timing items	Notes items
A0 Test type (antibody/antigen etc)	COVID patients (or all patients if single group study)
A1 Purpose	B1 Setting	D1.1 Test name	E1 Reference standard for cases including threshold	F1 What was the time interval between index and reference tests?	G1: Funding
A2 Design (and description of groups labelled [1] [2] …)	B2 Location (include name of institution if available)	D1.2 Manufacturer	E2 Samples used	F2 Did all patients receive the same reference standard?	G2: Publication status
A3 Recruitment	B3 Country	D1.3 Antibody targets	E3 Timing of reference standard (preferably since symptom onset only, if not from a different time points)	F3 Missing data	G3: Source (preprint or journal name)
A4 Were cases recruited prospectively or retrospectively?	B4 Dates	D1.4 Antigens used	E4 Was it blind to index test?	F4 Uninterpretable results	G4: Study author COI (including any manufacturer affiliations)
A5 Sample size (virus/COVID cases)	B5 Symptoms and severity	D1.5 Point‐of‐care or laboratory (is the test designed to be used at point‐of‐care or in laboratory, and was it used as point‐of‐care or in laboratory)?	E5 Did it incorporate index test?	F5 Indeterminate results	G5 Comment
A6 Inclusion and exclusion criteria	B6 Demographics	D1.6 Test method		F6 Samples or patients
A7 Comment	B7 Exposure history	D1.7 When were samples taken (preferably since symptom onset only, if not from a different time points)?	E6 Reference standard for non‐cases	F7 Comment
	B8 Comment	D1.8 Samples used	E7 Samples used
	Non‐COVID patients (if additional groups)	D1.9 Who applied the test	E8 Timing of reference standard (preferably since symptom onset only, if not from a different time points)
	C1.1 Group name	D1.10 How was positive defined?	E9 Was it blind to index test?
	C1.2 Source and time	D1.11 Blinded to reference standard	E10 Did it incorporate index test?
	C1.3 Characteristics	D1.12 Threshold predefined	E11 Comment
	C2.1 Group name	D1.13 Comment
	C2.2 Source and time
	C2.3 Characteristics
	C4 Comment

Date range (2020)	Definition of confirmed case	Definition of confirmed non‐case	Definition of suspect case	Definition of probable case	Role of serology in testing
10‐30 January	10‐30 January: no documentation to define at this time (before first date of global guidelines) 31 January onwards: a confirmed case is a person with laboratory confirmation of COVID‐19 infection, irrespective of clinical signs and symptoms. No prescribed test in laboratory guidelines, suggested tests from 10 January include broad coronavirus RT‐PCR (with sequencing of precise virus in test positives), whole genome sequencing, broad coronavirus serology on paired samples, microscopy, culture. (Lab 10 January) Four suggested tests from 17 January: broad coronavirus RT‐PCR (with sequencing of precise virus in test positives), NAAT for SARS‐CoV‐2 when it becomes available, whole genome sequencing, and broad coronavirus serology on paired samples. States that once specific NAAT assays are developed and validated, confirmation will be based on specific detection of unique sequences of viral nucleic acid by RT‐PCR.	None stated	No definition of 'suspect case' at this time, but case definitions for surveillance are defined as a combination of symptoms and exposure, with more severe symptoms requiring less evidence for exposure	No definition at this time	Serological testing may be useful to confirm immunologic response to a pathogen from a specific viral group, e.g. coronavirus. Best results from serologic testing requires the collection of paired serum samples (in the acute and convalescent phase) from cases under investigation.
31 January‐26 February		None stated	Suspect case defined as combination of symptoms and exposure, with more severe symptoms requiring less evidence for exposure	A suspect case with inconclusive laboratory results or is test‐positive using a pan‐coronavirus assay without laboratory evidence of other respiratory pathogens. (global 31 January)
27 February‐1 March		None stated	Suspect case defined as combination of symptoms and exposure, with more severe symptoms requiring less evidence for exposure, OR defined by symptoms requiring hospitalisation and an absence of alternative explanation.	A suspected case with inconclusive laboratory results (global 27 February)
2 March‐19 March	A person with laboratory confirmation of COVID‐19 infection, irrespective of clinical signs and symptoms. (global 31 January, 27 February, 20 March) Laboratory confirmation of cases by NAAT specific to SAR‐CoV‐2 such as real‐time reverse‐transcription polymerase chain reaction (rRT‐PCR) with confirmation by nucleic acid sequencing when necessary. The viral genes targeted so far include the N, E, S and RdRP genes. In areas with no known COVID‐19 virus circulation confirmation requires: NAAT positive for at least two different targets on the COVID‐19 virus genome, of which at least one target is preferably specific for COVID‐19 virus (or SARS‐like coronavirus) using a validated assay; OR NAAT‐positive result for betacoronavirus, and COVID‐19 virus identified by sequencing partial/whole genome of virus (sequence target larger or different from the amplicon probed in the NAAT assay). Discordant results should be resampled. In areas where COVID‐19 virus is widely spread a simpler algorithm might be adopted (e.g. RT‐PCR of a single discriminatory target)	One or more negative results do not rule out the possibility of COVID‐19 virus infection.			In cases where NAAT assays are negative and there is a strong epidemiological link to COVID‐19 infection, paired serum samples (in the acute and convalescent phase) could support diagnosis once validated serology tests are available. Serological assays will play an important role in research and surveillance but are not currently recommended for case detection.
19 March‐present				Probable case A suspect case for whom testing for the COVID‐19 virus is inconclusive. OR A suspect case for whom testing could not be performed for any reason.
NAAT: nucleic acids amplification test; RT‐PCR: reverse transcription polymerase chain reaction; Source: WHO 2020.

DOMAIN: PARTICIPANT SELECTION
Was a consecutive or random sample of patients enrolled?	This will be similar for all index tests, target conditions, and populations. YES: if a study explicitly stated that all participants within a certain time frame were included; that this was done consecutively; or that a random selection was done. NO: if it was clear that a different selection procedure was employed; for example, selection based on clinician's preference, or based on institutions. UNCLEAR: if the selection procedure was not clear or not reported.
Was a case‐control design avoided?	This will be similar for all index tests, target conditions, and populations. YES: if a study explicitly stated that all participants came from the same group of (suspected) patients. NO: if it was clear that a different selection procedure was employed for the participants depending on their COVID‐19 status or SARS‐CoV‐2 infection status; or if only participants with SARS‐CoV‐2 infection were included UNCLEAR: if the selection procedure was not clear or not reported.
Did the study avoid inappropriate exclusions?	Studies may have excluded patients, or selected patients in such a way that they avoided including those who were difficult to diagnose or likely to be borderline. Although the inclusion and exclusion criteria will be different for the different index tests, inappropriate exclusions and inclusions will be similar for all index tests: for example, only elderly patients excluded, or children (as sampling may be more difficult). This needs to be addressed on a case‐to‐case basis. YES: if a high proportion of eligible patients was included without clear selection. NO: if a high proportion of eligible patients was excluded without providing a reason; if, in a retrospective study, participants without index test or reference standard results were excluded. UNCLEAR: if the exclusion criteria were not reported.
Did the study avoid inappropriate inclusions?	Some laboratory studies may have intentionally included groups of patients in whom the accuracy was likely to differ, such as those with particularly low or high viral loads, or who had other diseases, such that the sample over‐represented these groups. This needs to be addressed on a case‐to‐case basis. Artificial spiked samples are a clear example. YES: if samples included were likely to be representative of the spectrum of disease. NO: if the study oversampled patients with particular characteristics likely to affect estimates of accuracy. UNCLEAR: if the exclusion criteria were not reported.
Could the selection of patients have introduced bias?	HIGH: if one or more signalling questions were answered with NO, as any deviation from the selection process may lead to bias. LOW: if all signalling questions were answered with YES. UNCLEAR: all other instances.
Is there concern that the included participants do not match the review question?	HIGH: for two‐group studies that included healthy or other disease controls, whether pre‐pandemic or contemporaneous; studies that only included people with COVID‐19 (whether reverse transcription polymerase chain reaction (RT‐PCR)‐confirmed only, participants meeting official guideline criteria); LOW: for single‐group studies recruiting participants with signs and symptoms of COVID‐19; or for two‐group studies where control groups suspected of COVID‐19 were separately recruited. UNCLEAR: if a description about the participants was lacking.
DOMAIN: INDEX TESTS
Were the index test results interpreted without knowledge of the results of the reference standard?	YES: if blinding was explicitly stated or index test was recorded before the results from the reference standard were available. NO: if it was explicitly stated that the index test results were interpreted with knowledge of the results of the reference standard. UNCLEAR: if blinding was unclearly reported.
If a threshold was used, was it prespecified?	YES: if the test was dichotomous by nature, or if the threshold was stated in the methods section, or if study authors stated that the threshold as recommended by the manufacturer was used. NO: if a receiver operating characteristic curve was drawn or multiple threshold reported in the results section; and the final result was based on one of these thresholds. UNCLEAR: if threshold selection was not clearly reported.
Could the conduct or interpretation of the index test have introduced bias?	HIGH: if one or more signalling questions were answered with NO, as even in a laboratory situation knowledge of the reference standard may lead to bias. LOW: if all signalling questions were answered with YES. UNCLEAR: all other instances.
Is there concern that the index test, its conduct, or interpretation differ from the review question?	For evaluations of laboratory‐based tests, HIGH: if tests were built in‐house, or if commercially available tests using SARS‐Cov antigens instead of SARS‐CoV‐2‐specific antigens. LOW: most other laboratory‐evaluations UNCLEAR: name of the test was withheld For evaluations of lateral flow assays, HIGH: if tests were built in‐house; if only serum or plasma instead of fingerprick or whole blood samples were used; if test evaluated in laboratory settings rather than at the point of care LOW: commercially available tests, using whole blood or fingerprick samples, and that were conducted in the intended setting for the test (i.e. point‐of‐care). UNCLEAR: name of the test was withheld; mixed sample types; or did not report the evaluation setting
DOMAIN: REFERENCE STANDARD
Is the reference standard likely to correctly classify the target condition?	We will define acceptable reference standards using a consensus process once the list of reference standards that have been used has been obtained from the eligible studies. For COVID‐19 cases YES: RT‐PCR; confirmed or suspected case using official criteria (WHO, CDC) or a clearly set out combination of signs/symptoms/exposure. NO: RT‐PCR not used, or if inadequate combination of clinical characteristics used in PCR negatives, e.g. computed tomography alone UNCLEAR: if definition of COVID‐19 was not reported For absence of COVID‐19 YES: if at least 2 negative RT‐PCR results reported if suspected COVID‐19 based on signs/symptoms; single negative RT‐PCR test for asymptomatic contacts or contemporaneous controls with no clinical suspicion of COVID‐19; only pre‐pandemic sources of control samples used. NO: single RT‐PCR or number of negative RT‐PCRs not reported for COVID‐19 suspects; no RT‐PCR reported (untested) for asymptomatic contacts or contemporaneous controls UNCLEAR: if timing of control samples (pre‐pandemic or contemporaneous) was not reported
Were the reference standard results interpreted without knowledge of the results of the index test?	YES: if it was explicitly stated that the reference standard results were interpreted without knowledge of the results of the index test, or if the result of the index test was obtained after the reference standard. NO: if it was explicitly stated that the reference standard results were interpreted with knowledge of the results of the index test or if the index test was used to make the final diagnosis. UNCLEAR: if blinding was unclearly reported.
Did the definition of the reference standard incorporate results from the index test(s)?	YES: if results from the index test were a component of the reference standard definition. NO: if the reference standard did not incorporate the index standard test. UNCLEAR: if it was unclear whether the results of the index test formed part of the reference standard.
Could the conduct or interpretation of the reference standard have introduced bias?	HIGH: if one or more signalling questions were answered with NO. LOW: if all signalling questions were answered with YES. UNCLEAR: all other instances.
Is there concern that the target condition as defined by the reference standard does not match the review question?	Applicability was judged primarily on the definition of disease‐positive. HIGH: if RT‐PCR alone used to define cases LOW: if clinical criteria, including RT‐PCR, were used to define cases, regardless of whether official criteria were used, as long as the criteria were explicitly described. UNCLEAR: if definition of COVID‐19 cases was not provided, including if some clinically diagnosed cases were included but the clinical criteria used were not described.
DOMAIN: FLOW AND TIMING
Did all participants receive the same reference standard?	YES: if all participants received the same reference standard (clearly no differential verification). NO: if (part of) the index test‐positives or index test‐negatives received a different reference standard. UNCLEAR: if it was not reported.
Were all participants included in the analysis?	YES: if it is clear that all eligible participants were included in the analyses. NO: if after the inclusion/exclusion process, participants were removed from the analyses for different reasons: no reference standard done, no index test done, intermediate results of both index test or reference standard, indeterminate results of both index test or reference standard, samples unusable. UNCLEAR: if it is not possible to determine whether all participants were included (e.g. from a STARD style participant flow diagram)
Did all participants receive a reference standard?	YES: if all participants received a reference standard (clearly no partial verification). NO: if only (part of) the index test positives or index test negatives received the complete reference standard. UNCLEAR: if it was not reported.
Were results presented per participant?	YES: if either only one sample per participant (regardless of disaggregation of results over time), or if multiple samples per participant but results are disaggregated by time period (at least week by week) NO: if multiple samples per participant and results are not disaggregated by time period UNCLEAR: if it is not possible to tell whether results presented are per participant or per sample
Could the participantflow have introduced bias?	HIGH: if one or more signalling questions were answered with NO. LOW: if all signalling questions were answered with YES. UNCLEAR: all other instances.
CDC: Centers for Disease Control; ICU: intensive care unit; RT‐PCR: real‐time polymerase chain reaction; SARS‐CoV‐2: severe acute respiratory syndrome coronavirus 2; WHO: World Health Organization

Study  (source)	Inclusion criteria method used to rule out COVID‐19	Instititution (recruitment dates)	Age (median)  n, % male	Exposure history  Symptoms/severity	Reference details (cases)	Missing or uninterpretable data
Single‐group studies estimating sensitivity and specificity
Cassaniti 2020 (B) (published; letter) 50 participants (50 samples)	COVID‐19‐suspected cases presenting at A&E with fever and respiratory syndrome (n = 50, including 38 RT‐PCR‐positive); 2 x RT‐PCR‐negative required to rule out disease (Additional groups reported in Cassaniti 2020 (A))	A&E; Pavia, Italy (not stated)	61.5 years 34, 68%	Not stated Not stated	RT‐PCR detecting RNA polymerase and E genes; nasal swab (On presentation at A&E)	Weakly positive results counted as test positive
Liu 2020a (preprint) 179 participants (179 samples)	Inpatients and outpatients attending hospital during pandemic including COVID‐19‐suspected cases (all inpatient, n = 114) and outpatients (n = 64) with 'other disease'. (n = 179, including 90 PCR‐confirmed and 5 clinically confirmed cases) Negative PCR and insufficient evidence for clinical confirmation required to rule out disease	Inpatient and outpatient; Wuhan, China (1 January‐12 March 2020)	[1] mean 76 years [2+3] mean 56 years [1] 60, 67% [2+3] 38, 43%	Not reported Of 90 RT‐PCR+, 44, 49% severe/critical cases	Clinical criteria (not clearly described) ≤ RT‐PCR; nasal and pharyngeal swabs (NR)	Per sample data by time period is based on
Long 2020 (A) (preprint) 164 participants (164 samples)	Cohort of close contacts of 2 index cases (n = 164, 16 PCR‐positive cases) 1 x RT‐PCR‐negative required to rule out disease	Close contacts; Wanzhou, China (31 January‐9 February)	Not stated Not stated	All exposed 151 (92%) asymptomatic	RT‐PCR; NP (within 17 days of contact with confirmed cases)	None stated
Paradiso 2020a (preprint) 191 participants (191 samples)	Symptomatic patients accessing A&E (n = 191, including 70 PCR‐positive) 1 x RT‐PCR‐negative required to rule out disease	A&E; Bari, Italy (23‐29 March)	58.5 years 116, 61%	Not stated 14, 9% asymptomatic	RT‐PCR (Allplex 2019‐nCoV Assay; Seegene, Seoul, Republic of Korea); NP, OP (Simultaneous)	1 D+ missing from results
Zhang 2020b (preprint) 228 participants (228 samples)	Suspected COVID‐19 cases admitted to fever clinic (n = 228, including 3 PCR‐positive) 1 x RT‐PCR negative required to rule out disease (review team excluded additional reported groups)	Inpatients, Shengjing, China (21 January‐16 February)	Mean 51 years (cases only) Not stated	1, 33% Wuhan contact history (cases only) Not stated	RT‐PCR (required presence of ORF1ab and N gene for positive result); NP, OP (Timing not stated)	Not stated
Zhang 2020d (preprint) 814 participants (814 samples)	Participants suspected of harbouring COVID‐19 (n = 814, including 154 cases; 122 RT‐PCR‐positive and 32 clinically diagnosed by CT) 1 x RT‐PCR negative required to rule out disease; unclear if CT used in all D‐ (n = 663)	Samples from 5 hospitals (in/outpatient not stated); centres including Wuhan, Shenyang and Beijing, China (Not stated)	Not stated	Not stated	Real‐time PCR kit (no details on threshold); CT used in at least some PCR‐negative NP swabs. (Timing not stated)	None stated
Single group studies estimating sensitivity alone
Du 2020 (published; letter) 60 participants (60 samples)	Single group of convalescent inpatients 6‐7 weeks after symptom onset (n = 60) Non‐COVID‐19 cases not included	Hospital inpatients; Wuhan, China (12 January‐5 February 2020)	Not stated	Not stated	Not described; not stated (During hospital stay)	None described
Gao 2020a (published; letter) 38 participants (38 samples)	Inpatient cohort of COVID‐19 patients confirmed by Chinese Government‐issued guidelines (5th edition) non‐COVID‐19 cases not included	Inpatient; Fuyang, China (22 January‐28 February 2020)	40.5 years 21, 55.3%	Not stated 3, 8% severe or critical, 35 mild	Chinese guideline (5th edition)	Not reported
Gao 2020b [A] (accepted manuscript (peer reviewed; pre‐proof) 22 participants (37 samples)	Confirmed COVID‐19 cases (n = 22) non‐COVID‐19 cases not included	Hospital inpatient; Shijiazhuang, Hebei, China (21 January‐24 February 2020)	40 years 14, 64%	11 (50%) recent travel to epidemic areas, 10 (45%) close contacts with confirmed COVID‐19 cases 22 (100%) typical CT findings; 'most' received oxygen therapy	RT‐PCR assay (2019‐nCoV RNA Test Kit, Daan Gene Company, China); Nasal and pharyngeal swab specimens	None described
Garcia 2020 (B) (preprint) 63 participants (63 samples)	Patients admitted with a clinical and radiological diagnosis of pneumonia of unknown aetiology but RT‐PCR‐negative (n = 63) non‐COVID‐19 cases not included Addional reported cohort extracted as Garcia 2020 (A)	Inpatient hospital (9 February‐2 April)	67 years 47, 74%	Not stated	Clinical diagnosis of COVID‐19 (no further detail); all PCR‐negative	None reported
Hu 2020a (preprint) 211 participants (993 samples)	Confirmed COVID‐19 patients (221) non‐COVID‐19 cases not included	Inpatient; Chongqing, China (23 January‐3 March)	Mean 47.8 years 135, 64%	Not stated 137, 62% with fever; 40, 19% severe	Chinese Government guidelines (version 6); included RT‐PCR	None described; text states 993 samples but only 409 reported for IgM and 507 for IgG
Jia 2020 (preprint) 57 participants (57 samples)	1. RT‐PCR confirmed (24) 2. Clinical diagnosis for RT‐PCR negative (2 x negative results) according to Chinese Government guideline (6th ed) (33) non‐COVID‐19 cases not included	Inpatients; Shenzhen, China (Not stated)	Not stated	Not stated	1. RT‐PCR 2. Chinese CDC guideline (6th ed). (1 to 34 days from exposure to first PCR test)	None described
Li 2020a (accepted for publication and undergone full peer review) 525 participants (525 samples)	COVID‐19 according to Chinese CDC guideline (5th ed) (525; 397 PCR‐positive)) non‐COVID‐19 cases not included	Potentially inpatient and outpatient; 6 provinces, China (Not stated)	Not stated	Not stated	Chinese CDC guideline (6th ed), including PCR; pharyngeal, sputum (Not stated)	None stated
Lippi 2020 [A] (published; letter) 48 participants (48 samples)	Participants with suspected COVID‐19; subgroup of cases (48/131 patients) with available data on days post‐symptom onset data can be included non‐COVID‐19 cases not included	Inpatients; Verona, Italy (Not stated)	Totlal sample of 131: mean 56 years 60/131, 46%	Not stated	RT‐PCR (Seegene Allplex 2019‐nCoV Assay. OP, NP swabs (During hospitalisation)	Excluded 83 patients with no time pso data
Liu 2020c (preprint) 133 participants (133 samples)	Patients diagnosed with SARS‐Cov‐2 according to Chinese CDC guideline (5th ed) (133) non‐COVID‐19 cases not included	Inpatients; Wuhan, China ( 17 February‐1 March)	Moderate 67.5 years; severe 68 years; critical 70 years 70, 53%	Not stated moderate 44, 33%; severe 52, 39%; critical 37, 29%	Clinical diagnosis (seems to be Chinese CDC guideline, 5th ed) Includes RT‐PCR (GeneoDx Biotech, Shanghai, China); 2 tests per participant; Table 2 refers to NP.	None described
Long 2020 (B) (preprint) 262 participants (363 samples)	RT‐PCR‐positive confirmed cases (n = 285). No further detail of inclusion or exclusion criteria.  Additional cohort extracted as Long 2020 (A); some additional cohorts excluded (see Characteristics of included studies) non‐COVID‐19 cases not included	Inpatients; Chongqing, China (38384)	47 years 158, 55.4%	103, 36% exposure to transmission sources 39, 14% severe or critical in ICU	RT‐PCR; nasal and pharyngeal swabs (during hospital stay)	23 patients with no information on time pso were excluded leaving 363 samples from 262 patients
Padoan 2020 (peer reviewed; published) 37 participants (87 samples)	Hospitalised patients with confirmed COVID‐19 (n = 37) non‐COVID‐19 cases not included	Inpatients; Padova, Italy (18 March‐26 March 2020)	Not stated	Not stated	RT‐PCR; NP (Not stated)	None described
Pan 2020a (peer reviewed; published) 105 participants (134 samples)	COVID‐19 patients according to CDC guideline (5th ed); confirmed by PCR (67) or clinical diagnosis (37) non‐COVID‐19 cases not included	Inpatients; Wuhan, China (Not stated (symptom onset 7 January‐18 February))	58 years 48, 46%	Not stated	RT‐PCR following WHO guidelines (BioGerm, Shanghai, China), Clinical diagnosis according to CDC guideline (5th ed); throat swabs (Not stated)	Data reported only for those with symptom onset information; 26 samples excluded
To 2020a [A] (peer reviewed; published) 23 participants (108 serum samples)	Confirmed COVID‐19 patients from 2 hospitals (n = 23, can only extract data for 16 with > 14‐day pso data) non‐COVID‐19 cases not included	Hospital inpatient, Hong Kong (22 January‐12 February)	Not stated 13/23 (57%) age: median 62 years (range 37–75)	Not stated 10/23 (43%) severe; 5/23(22%) admitted to ICU, 3/23(13%) required intubation, 2/23(9%) died Fever in 22/23 (96%) patients, cough in 5/23 (22%), chills in 4/23 (17%), dyspnoea in 4/23 (17%)	Laboratory‐confirmed ‐ not further described; NP or sputum (Unclear)	7/23 (30%) were not tested between days 14 and 30
Xiao 2020a (accepted manuscript; pre‐proof) 34 participants (34 samples)	Confirmed cases of COVID‐19 according to Chinese CDC (5th ed) (34) non‐COVID‐19 cases not included	Inpatients; Wuhan, China (1‐29 February)	49 years (review team estimated) 22, 65%	Not stated Not described	COVID‐19 according to CDC diagnosis and treatment guideline (5th ed)	None reported
Xie 2020a (accepted manuscript; pre‐proof) 56 participants (56 samples)	Participants with suspected COVID‐19 based on Chinese CDC (5th ed) criteria (n = 56, including 16 PCR confirmed) non‐COVID‐19 cases not included	Inpatients; Wuhan, China (15‐25 February 2020)	56.5 years 24, 43%	Not stated 34, 61% severe	[1] RT‐PCR QIAamp RNA virus kit (Qiagen, Heiden, Germany); NP and throat [2] clinical diagnosis (guideline, 5th edition	None reported
Xu 2020a (preprint) 10 participants (10 samples)	Confirmed (PCR) COVID‐19 cases (n = 10) non‐COVID‐19 cases not included	Hospital inpatients; Shanghai, China (Not stated)	Not stated 6, 60%	Not stated 10, 100% required oxygen	RT‐PCR (cycle threshold value (Ct) < 37 defined as positive and Ct ≥ 40 defined as negative; pharyngeal swab (Not stated)	None reported
Yongchen 2020 (peer reviewed; published) 21 participants (≥ 42 samples)	Participants with COVID‐19 (n = 16) and asymptomatic carriers (n = 5) non‐COVID‐19 cases not included	Mixed; Jiangsu, China (25 January‐18 March 2020)	37 years 13, 62%	Not stated 5, 24% severe; 5, 24% asymptomatic cases Illness severity defined according to the Chinese management guideline for COVID‐19 (version 6.0).	RT‐PCR, confirmed after 2 sequential positive respiratory tract sample results; throat swabs	None described
Zhang 2020a (preprint) 222 participants (222 samples)	Confirmed COVID‐19 patients (RT‐PCR detection or antibody assay) (n = 222) non‐COVID‐19 cases not included	Inpatients; Wuhan, China (admitted 13 January 13‐1 March)	62 years Not stated	Not stated 87, 39% severe	RT‐PCR or anti‐SARS‐CoV‐2 assay ; nasal or pharyngeal swabs (Not stated)	None reported
Zhang 2020c (peer reviewed; published) 16 participants (16 samples)	RT‐PCR‐confirmed COVID‐19 patients (n = 139); included those with around 10 days of medical treatment after admission (n = 16) non‐COVID‐19 cases not included	Inpatients; Wuhan, China (Not stated)	Not stated	Not stated	RT‐PCR	< 10 days' medical treatment (n = 123)
A&E: Accident and Emergency Department; CDC: Center for Disease Control; CT: computed tomography; CGIA: colloidal gold immunoassay; D+: disease positive: D‐: disease negative; ed: edition; ELISA: enzyme‐linked immunosorbent assay; HCW: healthcare worker; ICU: intensive care unit; LFA: lateral flow assay; n: number; NP: nasopharyngeal; NR: not reported; OP: oropharyngeal; PCR: polymerase chain reaction; pso: post‐symptom onset; RNA: ribonucleic acid; RT‐PCR: reverse transcriptase polymerase chain reaction; SARS‐CoV‐2: severe acute respiratory syndrome coronavirus 2; suppl: supplementary; TB: tuberculosis

Study  (source)	COVID‐19 cases (n)	Non‐COVID cases (n)  (including method of verification)	Institution (Recruitment dates)	Age (median)  n, % male	Exposure history Symptoms/severity	Reference details (cases)	Missing or uninterpretable data
Adams 2020 [A] (preprint) 182 participants (40 samples)	RT‐PCR confirmed COVID‐19 cases (n = 40)	Pre‐pandemic controls (n = 142); prior to December 2019	Acute hospital (n = 16), recovering HCWs (n = 6), convalescent (n = 18); UK (Not stated)	57y Not stated	Not stated Asymptomatic (n = 1); mild (n = 26); severe (n = 4); critical (n = 9)	RT‐PCR; nose/throat swabs (Not stated )	[B]–[J] tests evaluated in different numbers
Bendavid 2020 (preprint) 3481 samples participants (3324 samples)	COVID‐19 cases were obtained from 3 different sources (n = 157 specimens) Confirmed cases from manufacturer data (n = 85); local cases (PCR‐ and ELISA‐confirmed) (n = 37) or PCR‐confirmed (6‐10 days pso) (n = 35)	Non‐COVID‐19 cases were obtained from 13 different sources (n = 3324 specimens), Pre‐pandemic (10 sources; n = 2811); pandemic era PCR‐negative (n = 202); not stated (n = 311)	Multiple sources; USA, China, unclear (Not described)	Not stated	Not stated	PCR‐positive only (n = 35); PCR and IgG or IgM confirmed by ELISA (n = 37); not stated (n = 85)	None described
Burbelo 2020 [A] (preprint) 67 participants (140 samples)	SARS‐CoV‐2 cases confirmed by PCR (n = 35 in results, n = 39 in methods)	Pre‐pandemic blood donors (n = 32); prior to 2018 [Review authors excluded 3rd group with no reference standard reported (n = 10)]	Hospital (unclear whether inpatient or outpatient); San Diego, Seattle, Washington, USA (Not stated)	44 years 0.87	Not stated 13, 37% on a ventilator	RT‐PCR; nasal and/or throat swabs (No information)	none described
Cai 2020 (preprint) 443 participants (443 samples)	RT‐PCR confirmed (276)	Healthy, other controls; pre‐December 2019 (167)	Inpatient (cases only); Chongqing, China (Not stated)	48 years 151, 55%	99, 36% known exposure	RT‐PCR; no further details	None described
Cassaniti 2020 (A) (published; letter) 60 participants (60 samples)	COVID‐19‐positive patients in ICU (n = 30)  [Additional cohort reported in Cassaniti 2020 (B)]	Healthy volunteers with negative RT‐PCR results (n = 30)	Infectious Diseases Unit or ICU, Tertiary hospital; Pavia, Italy (Not stated)	73.5 years 25, 42%	Not stated	RT‐PCR detecting RNA polymerase and E genes; Respiratory samples (During patient care)	Weakly positive results counted as test positive
Chen 2020a (Accepted manuscript; peer reviewed, pre‐proof) 19 participants (19 samples)	RT–PCR positive samples (n = 7)	RT–PCR‐negative samples, but clinically suspicious for COVID‐19 (n = 12) [Additional group of 'normal' samples (n = 51) used to derive threshold]	Unclear, presumably inpatients; Guangzhou, China (Not described)	Not stated	Not stated	RT–PCR; not stated (Not stated; prior to LFA)	None reported
Dohla 2020 (peer reviewed; published) 49 participants (49 samples)	[1] Attendees at community screening centre for COVID‐19 (n = 12 PCR‐positive), [2] Stored samples from 10 patients with confirmed diagnosis of COVID‐19	[1] Attendees at community screening centre for COVID‐19 (n = 27 PCR‐negative)	Community screening centre [1] and unclear setting [2]; author institutions Bonn, Germany (Not stated)	46 years 25, 51%	Probable date of exposure identified in 22, 45% 5/49 (10%) asymptomatic. 71% dry cough; 65% fatigue; 46% runny nose (only %s reported)	[1] RT–qPCR (Altona Diagnostics) [2] RT–qPCR (unknown if same kit); throat swabs group [1]; not stated for group [2]. ([1] same time as index test. [2] not stated)	Weak signals counted as positive; no missing data reported
Freeman 2020 (preprint) 618 participants (618 samples)	Confirmed COVID‐19 cases (n = 99)	Pre‐pandemic healthy (n = 377) + other infection (n = 142)	Convalescent; USA (reference to CDC National Center for Immunization and Respiratory Diseases) (Not stated)	Not stated	Not stated	PCR; no further detail	None mentioned
Garcia 2020 (A) (preprint) 100 participants (100 samples)	Suspected COVID‐19 patients admitted to A&E; all RT‐PCR‐positive (n = 55)  [Third cohort reported as Garcia 2020 (B)]	Pre‐pandemic healthy controls (n = 45); 1 October‐30 November, 2019	Inpatient; Madrid, Spain (1 March‐6 April 2020)	63 years 33, 60%	Not stated	RT‐PCR	None described
Grzelak 2020 [A] (preprint) 542 participants (652 samples)	Hospitalized COVID‐19 patients (51) Review team excluded 2 additional cohorts with no reference standard (See COIS)	Pre‐pandemic sera from healthy individuals (491)	Inpatient; Paris, France (Not stated)	Not described 47, 74%	Not stated	Not stated	None reported
Guo 2020a (accepted manuscript; corrected proof now available online) 275 participants (343 samples)	Confirmed (82) or probable (58) COVID‐19 cases (provided 208 samples)	Pre‐pandemic acute lower respiratory tract infection (135) Healthy individuals (150) used to define threshold	Inpatients; Wuhan and Beijing, China (cases) (43,831)	Not stated	Not stated Confirmed cases ‐ 28, 34% severe Pobable cases ‐ 5, 9% severe	Confirmed: deep sequencing or qPCR assay Probable: cases ‐ clinical manifestation, chest X‐ray and epidemiology but no virus detected by deep sequencing or qPCR; throat (Not stated)	None reported
Infantino 2020 (accepted publication; peer reviewed; pre‐proof) 125 participants (125 samples)	[1] confirmed COVID‐19 cases (n = 61)	[2] pre‐pandemic (2018‐19) control group with rheumatic and infectious diseases (n = 44) [3] blood donors (winter 2019) (n = 20)	Inpatient; Florence, Italy (Not stated)	mean 59 years 26, 43%	Not stated 30, 49% mild to moderate symptoms 31, 51% severe pneumonia requiring admission to ICU	RT‐PCR (2 positive results required for confirmation); OP and NP swabs (Not stated)	None reported
Jin 2020 (peer reviewed; published) 76 participants (98 samples from 43 cases samples)	Laboratory confirmed COVID‐19 patients (n = 43) [Review team excluded results for 34 participants after becoming PCR‐negative]	COVID‐19 suspects, discharged with 2 x RT‐PCR‐negative results with an interval of 24 h and who quarantined at home (n = 33)	Hospital inpatients; Hangzhou, China (January to 4 Mar 2020)	47 years 17, 40%	Not stated [1] COVID‐19 patients: 27 (63%) fever; 26 (61%) cough [2] Non‐COVID‐19 patients: 24/43 (73%) fever; 15/33 (46%) cough	RT‐PCR; oral swab or sputum specimens (During hospital stay)	No data reported for 16 patients while PCR positive.
Lassauniere 2020 [A] (preprint) 112 participants (112 samples)	COVID‐19 PCR‐positive patients (n = 30) admitted to intensive care	Pre‐pandemic (n = 82) including blood donors (n = 10) and other infections (n = 72)	Intensive care; Hillerod, Denmark (Not stated)	Not stated	Not stated	Viral nucleic acid detection (no further detail)	Borderline results for tests [B] and [C] were considered test negative; for POC tests weak signals for IgM and IgG were considered positive. Some samples not tested with all assays.
Lin 2020a [A] (preprint) 159 participants (159 samples)	[1] Suspected COVID‐19 cases (epidemiological risk, clinical features and RT‐PCR respiratory specimen positive) from inpatient setting (specialised COVID‐19 hospital) (n = 79)	RT‐PCR negative controls (reportedly at least 3 x negative), including: [2] healthy volunteers; timing not reported, presumed contemporaneous (n = 29) [3] TB patients; timing not reported, presumed contemporaneous (n = 51)	Inpatients (specialised COVID hospital); Shenzhen, China (Not stated)	Not stated	Not stated	Epidemiological risk, clinical features and RT‐PCR respiratory specimen positive' 'GeneoDX kit (Taqman RT‐PCR method)	Only 65/79 D+ and 64/80 D‐ serum samples available for ELISA; reason not given.
Liu 2020b (preprint) 358 participants (358 samples)	Confirmed (153) or suspected (85) COVID‐19	Ordinary patients (70) and randomly sampled healthy blood donors (50); timing not reported, presumed to be contemporaneous	Inpatients; Hubei, China (6 ‐14 February)	55 years 138, 58%	Not stated Fever (87%); dry cough (54%); fatigue (33%). 235/238 (99%) had CT ground glass opacity/patchy shadowing	RT‐PCR (Daan Gene) targeting ORF1ab and N gene (≤ 40 Ct); Clinical diagnosis according to Chinese Government‐issued guideline (5th ed); pharyngeal swabs RT‐PCR sampling throughout inpatient stay	None reported
Liu 2020d [A] (evaluation; accepted manuscript) 314 participants (314 samples)	RT‐PCR‐confirmed COVID‐19 cases (n = 214)	Healthy blood donors, presumed to be contemporaneous (n = 100)	Inpatient, Hubei, China (18 January‐26 February)	Not stated	Not stated	RT‐PCR; pharyngeal swabs. Median 15 days pso (range 0–55 days)	None described
Lou 2020 [A] (preprint) 380 participants (380 samples)	Confirmed COVID‐19 cases according to Chinese Government‐issued guidelines (6th edition) (n = 80)	Healthy people enrolled from the community, presumed contemporaneous selection (n = 300)	inpatient; Hangzhou, China (19 January‐9 February 2020)	Mean 55 years 0.61	26, 33% critical	CDC guideline (6th ed); criteria described including PCR; deep sputum samples' (On admission)	Not all control group participants were tested by all index tests (range 100‐300/300)
Ma 2020a (preprint) 570 participants (216 samples from 87 cases samples)	Confirmed (PCR‐positive) COVID‐19 patients (n = 87)	[2] Pre‐pandemic healthy donors (n = 330) [3] Contemporaneous 'other diseases' (no mention of PCR) (n = 138) [4] Suspected COVID pneumonia but negative PCR (n = 15)	Inpatient; Hefei, China (26 January‐5 March 2020)	Not stated	Not stated 56, 67% clinically moderate 17 severe 5 critical "few mild" [page 7]	Chinese Government‐issued guidelines (7th edition) including RT‐qPCR; serum (During hospital admission as part of "routine clinical testing". Performed before index test)	For comparison of sensitivity and specificity of 2 antigens only 20/total of 479 control sera were used (20/138 from 'other disease' group)
Okba 2020c (accepted manuscript; early release) 54 participants (76 samples)	RT‐PCR‐confirmed SARS‐CoV‐2 cases (n = 9, 31 samples)	Contemporaneous healthy blood donors (n = 45)	Inpatient; Munich, Germany (occurred after 23 January, discovered (presume PCR‐positive) on 27 January 27)	Not stated	All identified through exposure to known cases Not stated	RT‐PCR; OP, NP (day 1‐5 of symptoms)	Indeterminate or unclear index results on graphs considered negative by review team
Qian 2020 (preprint) 2113 participants (2113 samples)	[1] Confirmed COVID‐19 cases (RT‐PCR‐positive) (n = 503) and [2] suspected COVID‐19 cases based on epidemiological history, clinical symptoms and chest X‐ray but 3 x PCR‐negative (n = 52)	Apparently contemporaneous controls, including: [3] hospitalised with non‐COVID‐19 conditions (PCR testing not described) (n = 972) [4] healthy controls (n = 586)	Hospital inpatients; Hubei and other provinces, China (Unclear)	Not stated	Not stated	RT‐PCR; NP ("early onset of the symptoms of COVID‐19")	None described
Wan 2020 [A] (preprint) 17 participants (36 samples)	SARS‐Cov‐2 positive cases confirmed by RT‐PCR (n = 7, 26 samples)	Prepandemic sera (n = 5); plus controls SARS‐Cov‐2 negative on two occasions (n = 5)	Inpatients; Singapore (Not stated)	Not stated	Not stated	RT‐PCR	not stated
Wang 2020a [A] (accepted manuscript) 86 participants (86 samples)	COVID‐19 patients, meeting Chinese Government guideline criteria (14)	Contemporaneous patients with different pathogen infections and related chronic diseases with no clinical symptoms or imaging evidence of COVID‐19 (no PCR testing reported) (72)	Inpatient; Nanchong, China (25 January‐15 February)	Not stated	Not stated	Chinese CDC guideline (5th ed)	none described
Xiang 2020a [A] (preprint) 98 participants (ELISA samples) , 126 participants (LFA samples) , 81 participants (PCR samples)	COVID‐19 patients according to WHO interim guidance (suppl data reports PCR results for a subgroup); (n = 63 for ELISA, n = 91 for GICA, some overlap of cases)	Contemporaneous healthy individuals (n = 35)	Inpatient; Wuhan, China (admitted 1‐28 January; sampled 2‐4 February)	ELISA 65 years; LFA 61 years ELISA 35, 56% male LFA 49, 54% male	Not stated ELISA 4, 6% severe LFA 4, 4%	WHO interim guidance (subgroup of 82 also have PCR results); (PCR using throat swabs) (Not stated (PCR at 6‐37 days post‐admission))	Not stated
Xiang 2020b (peer reviewed; published) 150 participants (216 samples from 85 cases samples)	[1] RT‐PCR confirmed cases (n = 85) [2] Suspected cases with COVID‐19 pneumonia manifestations and ≥ 2 negative RT‐PCR (n = 24) classed as D+ for review purposes	[3] Contemporaneous control group of healthy blood donors (hospital staff) or patients with other diseases in the same hospital (all PCR‐negative) (n = 60)	Hospital patients (likely inpatients but not explicit); Wuhan, China (19 January‐2 March 2020)	51 years 31, 26%	Not stated 18/85 (21%) severe	[1] RT‐PCR [2] Clinical manifestations and PCR ; NP and/or OP (Unclear)	Not stated
Zeng 2020a (accepted manuscript; pre‐proof) 63 participants (63 samples)	COVID‐19 cases (n = 27); no details of confirmation process	Healthy controls, presume contemporaneous but not stated (n = 36)	Hospital inpatient; Wuhan, China (Not stated)	62 years 14, 52%	Not stated 17, 63% severe	No information; 'confirmed'; No information (No information)	None reported
Zhao 2020a (accepted manuscript; pre‐proof) 386 participants (386 samples)	Confirmed RT‐PCR positive COVID‐19 cases (173)	Pre‐pandemic healthy individuals (213)	Inpatients; Shenzhen, China (11 January‐9 February)	48 years 84, 49%	126, 73% clear exposure 32, 18% critical	RT‐PCR; respiratory (Not stated)	inadequate plasma samples for 2 IgM tests and 1 IgG test
Zhao 2020b (preprint) 481 participants (481 samples)	Hospitalised and/or recovered COVID‐19 patients (n = 69)	Pre‐pandemic 'normal' samples ("strong negatives"); presumed healthy (n = 257) Contemporaneous 'normal' samples ("negatives"); presumed healthy (n = 155)	Hospital (no detail); multiple author institutions, China (Not stated)	Not stated	Not stated	Not described; "hospitalized and/or recovered patients confirmed SARS‐CoV‐2 virus infection."	None reported
Zhong 2020 [A] (published; letter) 347 participants (347 samples)	PCR‐positive COVID‐19 patients (n = 47)	Pre‐pandemic healthy controls (n = 300)	Not stated; China (Not described (symptom onset 15 January‐13 February))	48 years 16, 34%	Not stated 11, 24% severe (6) or critical (5)	PCR	None reported
A&E: Accident and Emergency Department; CDC: Center for Disease Control; COIS: Characteristics of included studies table; CT: computed tomography; CGIA: colloidal gold immunoassay; D+: disease positive: D‐: disease negative; ed: edition; ELISA: enzyme‐linked immunosorbent assay; HCW: healthcare worker; ICU: intensive care unit; LFA: lateral flow assay; n: number; NP: nasopharyngeal; NR: not reported; OP: oropharyngeal; PCR: polymerase chain reaction; pso: post‐symptom onset; RNA: ribonucleic acid; RT‐PCR: reverse transcriptase polymerase chain reaction; RT‐qPCR: reverse transcriptase quantitative polymerase chain reaction; SARS‐CoV‐2: severe acute respiratory syndrome coronavirus 2; suppl: supplementary; TB: tuberculosis;

Study	Test type	Index test (manufacturer)	Antigen	Antibodies measured (threshold)	Sample used	Index sample timing (days pso)	Data by time pso
Adams 2020 [A]	[A]^a Laboratory [B] to [J] LFAs	[A] ELISA (In‐house) [B] to [J] name withheld	[A] tri S‐based [B] to [J] details withheld	[A] IgG (> 0.4) and IgM (IgM > 0.07) (set in study) [B] and [C] not known [D] to [J] IgG and IgM (presumed from reported results)	Plasma	Day 4‐62 (median and range per group: acute 10 (4 to 27); recovering HCW 13 (8 to 19); convalescent 48 (31 to 62))	Yes; per week
Bendavid 2020	LFA	No details (Premier Biotech, Minneapolis, MN))	Not specified	IgG, IgM (threshold not specified)	Serum, plasma, fingerstick blood, venous whole blood	Not described	No
Burbelo 2020 [A]	Laboratory	LIPS (in‐house)	[A] N‐based [B] S‐based	Appears to be total Ab (threshold set in healthy control sample)	plasma or serum	Day 2‐50	Yes; ≤ 14 d, and > 14 d
Cai 2020	Laboratory	CLIA (in‐house)	S‐based	IgM, IgG (both ≥ 0.7 CL)	Serum (day 2‐27 pso)	Day 2‐27	No
Cassaniti 2020 (A)	LFA	CGIA: VivaDiag COVID‐19 IgM/IgG (VivaChek)	Not stated	IgM, IgG (visible line)	Serum or whole blood	On presentation at A&E	No
Cassaniti 2020 (B)	LFA	CGIA: VivaDiag COVID‐19 IgM/IgG (VivaChek)	Not stated	IgM, IgG (visible line)	Serum or blood	Median 7 days (IQR 4 to 11) after first test	No
Chen 2020a	LFA	FIA (in‐house; using lanthanide‐doped polystyrene nanoparticles)	N‐based	IgG (threshold: At (florescence peak of test line)/Ac (florescence peak of control line) ratio (R) > 0.0666 )	Serum	Not stated	No
Dohla 2020	LFA	CGIA (suspect this is a description of an anonymised test; no manufacturer stated)	SARS‐CoV‐2 antigen	IgG/IgM (weakly visible or clearly visible (strong positive) test line)	Fingerprick blood (n = 39 in cohort [1]); stored serum for cohort [2]	Median time from exposure–to–test 18.5 d (IQR 15 to 24)	No
Du 2020	Laboratory	Not stated; coded as CLIA based on reported threshold in AU/mL (Manufacturer not reported)	Not stated	IgM, IgG (threshold > 10 AU/mL)	Not stated	day 22 to > 35	Yes; by week from day 22
Freeman 2020	Laboratory	ELISA (in‐house)	S‐based	IgG and IgM (based on optical density signal)	Serum	All day ≥ 10	No
Gao 2020a	LFA	CGIA (Innovita Biological Technology Co)	Not reported	IgG, IgM (coloured line)	Serum	day 0 to > 14	Yes; by week from day 22
Gao 2020b [A]	[A] Laboratory [B] CGIA [C] Laboratory	[A] CLIA [B] CGIA [C] ELISA (all Beier Bioengineering Company, Beijing)	[A], [B], and [C] all S‐ and N‐based	IgG and IgM ([A] ≥ 8 arbitrary unit (AU)/mL; [B] visible line; [C] method to calculate threshold reported )	Serum	Day 1‐24	Yes; by week
Garcia 2020 (A)	LFA	CGIA, AllTest COV‐19 IgG/IgM kit (AllTest Biotech, Hangzhou, China)	Not reported	IgG, IgM (visible line for either)	Serum	Day 0 to ≥ 14	Yes; by week
Garcia 2020 (B)	LFA	CGIA, AllTest COV‐19 IgG / IgM kit (AllTest Biotech, Hangzhou, China))	Not reported	IgG and IgM (visible line for either)	Serum	Day 8 to ≥ 14	Yes; by week
Grzelak 2020 [A]	[A] to [E] all Laboratory	5 tests evaluated: [A] and [B] LIPS (in‐house) [C] and [E] ELISA [D] S‐flow	[A] S1‐based [B] and [C] N‐based [D] S‐based [E] tri‐S‐based	a. IgG b. total Ab c. IgM or IgG d. total Ab (Not clearly stated, plotted on Figure 1)	Serum	Not stated; day 2‐18 for 5 patients	No
Guo 2020a	Laboratory	In‐house ELISA	N‐based	IgM, IgG, IgA (threshold set in healthy control sample)	Blood/plasma	Day 1‐39	Yes; week 1 only
Hu 2020a	Laboratory	Magnetic MCLIA kit (Bioscience Co., Ltd (Chongqing, China))	N‐ and S‐based	IgM, IgG (S/CO ≥ 1.0 considered positive (ratio of the chemiluminescence signal to the cut‐off value)	Serum	Day 1 to > 37	Yes; by week
Infantino 2020	Laboratory	SARS CoV‐2 IgM and IgG CLIA kits (Shenzhen YHLO Biotech Co)	N‐ and S‐based	IgM, IgG (multiple thresholds reported, including manufacturer recommended threshold ≥ 10 AU/mL )	Blood (discussion mentions serum)	Day 8‐19	No
Jia 2020	LFA	FIA method (Beijing Diagreat Biotechnologies)	Not described	IgM (≥ 0.88 Flu) IgG (≥ 1.02 Flu) (threshold set in healthy control sample)	Not stated	Not stated	No
Jin 2020	Laboratory	SARS CoV‐2 IgM and IgG CLIA kits (Shenzhen YHLO Biotech Co)	N‐ and S‐based	IgM, IgG (> 10 AU/mL)	Serum	Day 1‐55	Yes; by week
Lassauniere 2020 [A]	[A] to [C] laboratory, [D] to [I] LFA	[A] ELISA (Beijing Wantai) [B] IgG ELISA (EUROIMMUN) [C] IgA ELISA ELISA (EUROIMMUN) [D] to [F] all presumed to be CGIA [D] Dynamiker Biotech 2019‐nCOV IgG/IgM Rapid Test [E] CTK Biotech ‐ OnSiteTM COVID‐19 IgG/IgM Rapid Test [F] Autobio Diagnostics Anti‐SARS‐CoV‐2 Rapid Test [G] Artron Labs Coronavirus Diseases 2019 (COVID‐19) IgM/IgG Antibody Test [H] Acro Biotech 2019‐nCoV IgG/IgM Rapid Test Cassette [I] Hangzhou All test 2019‐nCoV IgG/IgM Rapid Test Cassette	[A] S‐based [B] and [C] S1‐based [D] to [I] not stated	[A] Total Ab (calculated negative control value to 0.160) [B] IgG and [C] IgM (ratio < 0.8 is considered negative, ≥ 0.8 and < 1.1 borderline, and ≥ 1.1 positive) [D] to [I] IgG/IgM (Visual line change)	Serum	Day 7 to ≥ 21	Yes
Li 2020a	LFA	CGIA (Jiangsu Medomics Medical Technologies)	S‐based	IgM, IgG (coloured line)	Serum, plasma	Not stated; for 1 site (n = 58), sampling day 8‐33	No
Lin 2020a [A]	[A] and [B] laboratory	[A] In‐house CLIA [B] ELISA (Darui Biotech, China)	[A] and [B] N‐based	[A] IgM (RLU 162296); IgG (RLU 336697) (threshold set using ROC analysis) [B] IgM, IgG	Serum	Day 0 to ≥ 14	Yes; by week
Lippi 2020 [A]	[A] and [B] laboratory	[A] MAGLUMI 2019‐nCoV CLIAs (Snibe Diagnostics ‐Shenzhen New Industries Biomedical Engineering Co., Ltd, ) [B] ELISAs (Euroimmun AG, Lübeck, Germany)	[A] N‐ and S‐based [B] Not stated	[A] IgM or IgG (≥ 1.10 AU/mL) [B] IgA or IgG (≥ 1.1 (absorbance of patient sample/absorbance of calibrator))	[A] Serum or plasma [B] Not stated	Day < 5‐21	Yes; 5 day intervals
Liu 2020a	LFA	CGIA (Not stated: 'Chinese biotechnology company')	Not stated	IgG, IgM (visible line)	Serum	Day 0 to ≥ 14	Yes; by week
Liu 2020b	Laboratory	ELISA kit (Lizhu, Zhuhai, China)	N‐based	IgM, IgG (threshold set in healthy control sample)	Serum	Day 0 to ≥ 16	Yes; 5‐day intervals
Liu 2020c	Laboratory	iFLash‐SARS‐CoV‐2 CLIA (Shenzhen YHLO Biotech) [based on company contact]	Not described	IgM, IgG (not stated)	Serum	Not stated	No
Liu 2020d [A]	Laboratory	[A] ELISA (Hotgen, Beijing, China) [B] ELISA (Lizhu, Zhuhai, China)	[A] S‐based [B] N‐based	IgM, IgG (threshold not stated but method of calculation reported)	Serum	Day 0‐30	Yes; unequal intervals
Long 2020 (A)	Laboratory	Magnetic CLIA (Bioscience (Chongqing) Co., Ltd)	N‐ and S‐based	IgM, IgG (threshold not stated)	Serum	Not stated; 21‐31 days after PCR test	No
Long 2020 (B)	Laboratory	Magnetic CLIA (Bioscience (Chongqing) Co., Ltd)	N‐ and S‐based	IgM, IgG (threshold not described)	Serum	Day 2 to ≥ 23	Yes; by week
Lou 2020 [A]	[A] and [C] laboratory [B] LFA	[A] ELISA (Beijing Wantai) [B] CGIA (Beijing Wantai) [C] CLIA (Xiamen InnoDx)	[A] N‐ and S‐based [B] and [C] not stated	IgG, IgM, Ab (thresholds as per manufacturer; NR)	Serum	Day 0‐29	Yes; by week
Ma 2020a	Laboratory	CLIA (in‐house)	S‐based (RBD)	IgM, IgG, IgA (ROC analysis to determine optimal cut‐off in RLU, which is not stated	Serum	Day 4‐41	Yes; 5‐day intervals
Okba 2020a	Laboratory	ELISA, beta version (EUROIMMUN)	Not stated	IgA, IgG IgM, IgG (threshold not stated but method of calculation reported)	Serum	Day 3 to > 23	Yes; by week
Padoan 2020	Laboratory	CLIA ‐ MAGLUMI 2000 Plus nCoV (Snibe Diagnostics)	Not stated	IgM (1.0 AU/mL); IgG (1.1 AU/mL)	Serum	Day 0 to ≥ 13	Yes; by week
Pan 2020a	LFA	CGIA (Zhuhai Livzon Diagnositic Inc)	Not described	IgM, IgG (appearance of T line)	Serum or plasma	Day 1 to ≥ 15	Yes; by week
Paradiso 2020a	LFA	VivaDiag (Jiangsu Medomics Medical Technologies) [VivaChek?]	S‐based	IgM, IgG (both indicated by presence of red/purple line)	Venous blood	Day 0 to > 15	No
Qian 2020	Laboratory	CLIA (states analysed using fully automated immune analyser from Shenzhen YHLO Biotech Co)	N‐ and S‐based	IgM and IgG (RLU ≥ 10 AU/mL)	Serum	Not stated	Patients
To 2020a [A]	Laboratory	EIAs (in‐house, considered with ELISA tests for analysis purposes)	[A] N‐based [B] S‐based	IgG, IgM (set as the mean value of 93 anonymous archived serum specimens from 2018, plus 3 SDs)	Used serum remnant from blood samples taken for routine biochemical testing	Day ≥ 14 (for subgroup with 2x2 data)	Samples
Wan 2020 [A]	[A] and [B] laboratory	[A] IIFT (EUROIMMUN) [B] In‐house ELISA	[A] and [B] both SARS‐CoV	a. Total antibody (≥ 400) b. IgM, IgG (threshold not stated)	Serum	Day 3‐24	Yes; per week
Wang 2020a [A]	[A] Laboratory [B] LFA	[A] ELISA (Beijing Hotgen Biotechnology Co) [B] CGIA (Beijing Hotgen Biotechnology Co)	Not stated	IgM ([A] not stated; [B] coloured line)	Serum	Day 3‐7	Yes (week 1 only)
Xiang 2020a [A]	[A] Laboratory [B] LFA	[A] ELISA (Zhu Hai Livzon Diagnostics) [B] CGIA (Zhu Hai Livzon Diagnostics)	Not stated	IgM, IgG ([A] threshold not stated; [B] coloured line)	[A] Serum, [B] Plasma	Not stated (can be estimated as 5‐35 days post‐admission)	No
Xiang 2020b	Laboratory	ELISA (ELISA kits, Zuhai Livzon Inc)	N‐based	IgG, IgM (method to calculate threshold reported	Serum	day 0 to > 21	Yes; per week
Xiao 2020a	Laboratory	CLIA (Shenzhen YHLO Biotechnology Co. Ltd)	Not described	IgM, IgG (≤ 10 AU/mL)	Blood	Day 1‐49	Yes; per week
Xie 2020a	Laboratory	CLIA (Shenzhen YHLO Biological Technology)	N‐ and S‐based	IgG, IgM (≥ 10 AU/mL)	Serum	Day 0‐41	No
Xu 2020a	LFA	CGIA (in‐house)	S‐based	IgG, IgM (coloured line)	Not stated	Day 15‐30 of observation	No
Yongchen 2020	LFA	CGIA (Innovita Co. Ltd, China)	N‐ and S‐based	IgG, IgM (coloured line)	Serum	Day 8‐42	Yes; by week
Zeng 2020a	Laboratory	ELISA (Zhuhai Livzon Diagnostics)	Not stated	IgG and IgM (OD = 0.105)	Serum	Day 3‐39; can extract for day 6 only	Yes; week 1 only
Zhang 2020a	Laboratory	CLIA ‐ iFlash‐SARS‐CoV‐2 IgG and iFlash‐SARS‐CoV‐2 (Shenzhen YHLO Biotech Co. Ltd.)	Not described	IgM, IgG (threshold not described)	Serum	Day 1‐35	No
Zhang 2020b	Laboratory	CLIA ‐ iFlash‐SARS‐CoV‐2 (Shenzhen YHLO Biotechnology Co Ltd) [derived from company contact]	N‐ and S‐based	IgM, IgG (> 10.0 AU/mL); AU ‐ antibody concentration per mL	Serum (frozen until analysis)	Day 4‐18	No
Zhang 2020c	Laboratory	ELISA (in‐house; anti‐SARSr‐CoV)	N‐based (SARS‐CoV)	IgM, IgG (threshold not described)	Serum	Day 0 and day 5	Yes; week 1 only
Zhang 2020d	LFA	CGIA (in‐house)	S‐based	Total antibodies (IgM, IgG) (Visible test and control lines)	Serum	Not stated	No
Zhao 2020a	Laboratory	ELISA (Shenzhen YHLO Biotech Co)	N‐ and S‐based	Ab, IgM, IgG (Not stated)	Plasma	Day 1‐39	Yes; week 1, 2 and 3+
Zhao 2020b	Laboratory	ELISA (in‐house)	S1‐based	Total antibodies (IgG or IgM) (threshold calculation method reported)	Plasma	Not stated; n = 45 during week 1	No
Zhong 2020 [A]	Laboratory	[A] and [B] in‐house ELISA [C] CLIA (author institution is Maccura Biotech)	[A] N‐based [B] S‐based [C] N‐ and S‐based (unclear)	IgM, IgG (optimal cut‐off based on ROC analysis)	Serum	Day 1‐29	No
A&E: Accident and Emergency Department; Ab: antibody; AU: arbitrary units; CGIA: colloidal gold immunoassay; CL: chemilumonescence units; CLIA: chemiluminescence immunoassay; d: days; ELISA: enzyme‐linked immunosorbent assay; FIA: fluorescence immunoassay; Flu: fluorescence units; HCW: healthcare workers; IIFT: indirect immunofluorescence assay; IQR: interquartile range; LFA: lateral flow assay; LIPS: luciferase Immunoprecipitation System; mL: millilitre; N‐based: nucleocapsid protein; NR: not reported; OD: Optical density; pso: post‐symptom onset; RBD: receptor binding domain; RLU: relative light units; ROC: receiver operating characteristics; S‐based: spike protein; SD: standard deviation; S‐flow: flow‐cytometry based test; SARS‐CoV‐2: severe acute respiratory syndrome coronavirus 2; SD: standard deviation

Test	Study	From paper	From company documentation/website
ELISA: Enzyme‐linked immunosorbent assay
Beijing Beier Bioengineering	Gao 2020b [C]	No product codes provided (Study author contacted 29 May 2020)	No IFU and not on company website, no product code identified
Beijing Hotgen	Wang 2020a [A]	ELISA (20200101 and 20200201)	No IFU, no product code identified www.hotgen.com.cn/ky/upt.html Unclear if test on website is ELISA although the company do produce ELISAs
Beijing Hotgen	Liu 2020d [A]	No product code provided ; “The rS‐based ELISA kit (Hotgen, Beijing, China)” Study author contacted 1 June 2020
Beijing Wantai	Lassauniere 2020 [A]	SARS‐CoV‐2 Ab ELISA (CE‐IVD) (WS‐1096)	www.sanbio.nl/ws-1096
	Lou 2020 [A]	IgM, IgG; no product code reported in paper Study author responded: ELISA‐Ab lot number NCOA20200201B ELISA‐IgM lot number NCOM20200202B ELISA‐IgG lot number NCOnG20200201B
	Zhao 2020a	No product code reported; “(ELISA) kits supplied by Beijing Wantai Biological Pharmacy Enterprise Co” Study author contacted 1 June 2020
Darui Biotechnology	Lin 2020a [A]	No product code reported; “commercial enzyme‐linked immunosorbent assay kit (Darui Biotech, CHINA)” Study author contacted 1 June 2020	No IFU, no product code on website (www.daruibiotech.com/eproduct/index_33.html)
EUROIMMUN	Lassauniere 2020 [B]; Lassauniere 2020 [C]	Anti‐SARS‐CoV‐2 IgG (EI 2668‐9601 G) Anti‐SARS‐CoV‐2 IgA (EI 2606‐9601 A)	IFU: Anti‐SARS‐CoV‐2 ELISA (IgG) (EI 2606‐9601 G) IFU: Anti‐SARS‐CoV‐2 ELISA (IgA) (EI 2606‐9601 A)
	Lippi 2020 [B]	No product code reported; “Anti‐SARS‐CoV‐2 IgA and IgG … ELISAs; Euroimmun AG, Lübeck, Germany” Study author replied but could not supply product code
	Okba 2020a	No product code reported; “β‐versions of 2 commercial kits (EUROIMMUN)” (These are Beta versions)	Not available
Zhuhai Livzon	Xiang 2020a [A]	IgG/IgM antibody ELISA kits (lot number 2020010108)	No IFU identified; website only has the lateral flow assay en.livzon.com.cn/product/98.html No product code identified
	Xiang 2020b	ELISA kits (lot numbers IgM 20200308, IgG 20200308)
	Zeng 2020a	No product code reported: ELISA “assay kits (Zhuhai Livzon Diagnostics INC.)” Study author contacted 1 June 2020
Zhuhai Lizhu	Liu 2020b	No product code reported: ELISA kit “(Lizhu, Zhuhai, China )” Study author contacted 1 June 2020	Presumed to be same as above, following contact with FIND
Zhuhai Lizhu	Liu 2020d [B]	No product code reported: ELISA kit (Lizhu, Zhuhai, China) Study author contacted 1 June 2020	Presumed to be same as above, following contact with FIND
CLIA: chemiluminescence immunoassay
Beijing Beier Bioengineering	Gao 2020b [A]	No product codes provided (Study author contacted 29 May 2020)	No IFU, not on website; no product code identified
Bioscience Co (Chongqing)	Hu 2020a	No product code reported; “(MCLIA) kit supplied by Bioscience Co., Ltd (Chongqing, China)“ Study author contacted 1 June 2020	Review authors unable to find this company; no product code identified
Bioscience Co (Chongqing)	Long 2020 (A); Long 2020 (B)	No product code reported; “(MCLIA) kit supplied by Bioscience Co., Ltd China)“ Study author supplied NMA approval numbers only: MCLA IgG: China National Medical Products Administration approval number 20203400183; MCLA IgM: China National Medical Products Administration approval number20203400182
Shenzhen YHLO	Infantino 2020	No product code reported; “IgM and IgG CLIA kits were from Shenzhen YHLO Biotech Co., Ltd (China),” Study author provided details: IgG anti‐SARS Cov2 C86095G; IgM C86095M LOT NUMBER 207	Company flyer: iFlash‐SARS‐CoV‐2 IgG (C86095G) iFlash‐SARS‐CoV‐2 IgM (C86095G)
	Jin 2020	No product code reported; “(CLIA) kits used in this study were supplied by Shenzhen YHLO Biotech Co., Ltd (China)” Study author contacted 1 June 2020
	Liu 2020c	No product code reported; “SARS‐CoV‐2 antibody detection kit (YHLO Biotech, Shenzhen, China” Study author contacted 1 June 2020
	Xiao 2020a	No product code reported; “IgM and IgG were analyzed by … CLIA … (Shenzhen Yahuilong Biotechnology Co., Ltd). Study author contacted 1 June 2020
	Xie 2020a	No product code reported; “IgG and IgM assays were purchased from YHLO Biological Technology Co., Ltd., Shenzhen, China” Study author contacted 1 June 2020
	Zhang 2020a	No product code reported; “(CLIA) Assays panel (Shenzhen YHLO Biotech Co., Ltd., Shenzhen, China)” Study author contacted 1 June 2020
	Zhang 2020b	No product code reported; “CLIA detection kit from Shenzhen Yahuilong Biotechnology Co Ltd” Study author contacted 1 June 2020
Snibe Diagnostic ‐ MAGLUMI	Lippi 2020 [A]	No product code reported; “MAGLUMI 2019‐nCoV IgG and IgM”. (IgM ‐ 130219016M; IgG – 130219015M) Study author contacted 1 June 2020 Study author replied 1 June 2020 with IFU (no lot numbers provided; code from IFU added above)	From image on website: IgM ‐ Ref 130219016M; Lot 2712000501 IgG ‐ Ref 130219016M; Lot 2722000501 (www.snibe.com/zh_en/en_newsView.aspx?id=576)
Snibe Diagnostic ‐ MAGLUMI	Padoan 2020	No product code reported; “MAGLUMI 2000 Plus (New Industries Biomedical Engineering Co., Ltd [Snibe], Shenzhen, China)” Study author supplied details: ‐ for SARS‐CoV‐2 IgG lot number used for all the 87 measurements: 2722000102, kit number 8131; ‐ for SARS‐CoV‐2 IgM lot number used for all the 87 measurements: 2712000201, kit number 5122
Xiamen InnoDx Biotech	Lou 2020 [C]	No product code reported; “CMIA reagents were supplied by Xiamen InnoDx Biotech Co., Ltd., China Study author supplied following details: CMIA‐Ab product code CT0669 lot number 20200201 CMIA‐IgM product code CT0667 lot number 20200201	Review authors unable to find website for this company
Other laboratory‐based tests
EUROIMMUN	Wan 2020 [A]	No product code reported; “Anti‐SARS CoV Indirect 62 Immunofluorescence test (IIFT) (IgM & IgG) by Euroimmun (Germany)” (Test uses SARS‐Cov not SARS‐CoV‐2)
Lateral flow assays
Acro Biotech	Lassauniere 2020 [H]	2019‐nCoV IgG/IgM Rapid Test Cassette (INCP‐402)	Code from IFU and Assay Genie website: INCP‐402
Artron Laboratories	Lassauniere 2020 [G]	Coronavirus Diseases 2019 (COVID‐19) IgM/IgG Antibody Test (A03‐51‐322),	Brochure only; but no product code www.artronlab.com/products/CoVBrochure-ver3.pdf
Autobio Diagnostics	Lassauniere 2020 [F]	Anti‐SARS‐CoV‐2 Rapid Test (RTA0204)	Code from IFU: Anti‐SARS‐CoV‐2 Rapid Test (RTA0203)
Beijing Beier Bioengineering	Gao 2020b [B]	No product codes provided (Study author contacted 29 May 2020)	No IFU and not on company website; Distributor: www.unifier.one/en/beier-new-2019-coronavirus-covid-19-rapid-test.html 2019‐ New Coronavirus IgM/IgG Rapid Test Casette (WB/S/P) No product code
Beijing Diagreat	Jia 2020	COVID IgM/IgG antibodies kit, which have sent to Beijing Institute of Medical Device Testing (BIMT) for product verification (lot: 20200214)	Manual from 2019‐nCoV IgM Antibody Determination Kit (immunochromatographic Assay) Product No. P11802 2019‐nCoV IgG Antibody Determination Kit (Immunochromatographic Assay) Product No. P11801
Beijing Hotgen	Wang 2020a [B]	Kit provided by Beijing Hotgen Biotechnology Co., Beijing, China: (lot number 20200208 and 105 20200229 for GICA)	No IFU, on website but no product code www.hotgen.com.cn/ky/upt.html Coronavirus disease (COVID‐19) Antibody Test (Colloidal Gold)
Beijing Wantai	Lou 2020 [B]	No product code reported Study author provided: LFIA‐Ab lot number JNB20200202F LFIA‐IgM lot number JNM20200203F LFIA‐IgG lot number JNG20200201F	Code from IFU: WJ‐2701, WJ‐2710, WJ‐2750 Website: Rapid test for coronavirus Ab (CE‐IVD) (WJ‐2750 www.sanbio.nl/wj-2750)
CTK Biotech ‐ OnSite	Lassauniere 2020 [E]	OnSite COVID‐19 IgG/IgM Rapid Test (R0180C)	IFU: OnSite COVID‐19 IgG/IgM Rapid Test R0180C
Dynamiker Biotechnology	Lassauniere 2020 [D]	2019‐nCOV IgG/IgM Rapid Test (DNK‐1419‐1)	IFU: 2019‐nCOV IgG/IgM Rapid Test Catalogue No: DNK‐1419‐1
Hangzhou Alltest	Lassauniere 2020 [I]	2019‐nCoV IgG/IgM Rapid Test Cassette (INCP‐402)	IFU; 2019‐nCoV IgG/IgM Rapid Test Cassette (Whole blood/serum/plasma) Package Insert INCP‐402
Hangzhou Alltest	Garcia 2020 (A) Garcia 2020 (B)	AllTest COV‐19 IgG / IgM kit (no product code) Study author provided IFU (product code NCP‐402)
Innovita Biological	Gao 2020a	No product code reported Study author contacted 1 June 2020	IFU: 2019‐nCoV Ab Test (Colloidal gold); Catalogue No. YF 319C
Innovita Biological	Yongchen 2020	No product code reported Study author provided lot number: 20200205
Jiangsu Medomics	Li 2020a	No product code reported “SARS‐CoV‐2 rapid IgG‐IgM combined antibody test kit” Study author contacted 1 June 2020	Review authors were unable to find this company; study was also provided to review authors by Lomina (www.test-covid19.com/); no product code identified
Vivachek ‐ VivaDiag	Paradiso 2020a	No product code reported; “Viva‐Diag^TM kit produced by Jiangsu Medomics Medical Technologies kit (https://www.vivachek.com/vivachek/English/prods/prod-covid19.html)”; link no longer active. test considered to be Vivachek test Study author contacted 1 June 2020	Package insert VivaDiag SARS‐CoV‐2 IgM/IgG Rapid Test (VID35‐08‐011 / VID35‐08‐012 / VID35‐08‐013 / VID35‐08‐014 / VID35‐08‐015)
Vivachek ‐ VivaDiag	Cassaniti 2020 (A) Cassaniti 2020 (B)	No product code reported; “VivaDiag COVID‐19 IgM/IgG from VivaChek”; study also provided by Vivachek following company contact Study author provided lot number E2002002, REF VID35‐08‐011
Zhuhai Livzon	Pan 2020a	No product code reported Study author contacted 1 June 2020	Product flyer; Diagnostic Kit for IgM/IgG Antibody to Coronavirus (SARS‐CoV‐2); Catalogue number: 01040048
	Xiang 2020a [B]	IgG/IgM antibody GICA kits (lot number 2001010220)
FIND: Foundation for Innovative Diagnostics; IFU: instructions for use; NMA: China National Medical Products Administration

Test	No. of studies	No. of participants
1 IgG (all time points)	62	11748
2 IgG (1 to 7 days)	33	585
3 IgG (8 to 14 days)	34	1220
4 IgG (15 to 21 days)	32	1108
5 IgG (22 to 35 days)	20	495
6 IgG (over 35 days)	12	259
7 IgM (all time points)	58	11436
8 IgM (8 to 14 days)	31	1166
9 IgM (1 to 7 days)	34	658
10 IgM (15 to 21 days)	30	1057
11 IgM (22 to 35 days)	18	492
12 IgM (over 35 days)	12	222
13 IgG/IgM (all time points)	44	9496
14 IgG/IgM (1 to 7 days)	17	259
15 IgG/IgM (8 to 14 days)	21	608
16 IgG/IgM (15 to 21 days)	21	692
17 IgG/IgM (22 to 35 days)	16	152
18 IgG/IgM (over 35 days)	9	153
19 IgA (all time points)	5	1278
20 IgA (1 to 7 days)	4	100
21 IgA (8 to 14 days)	4	65
22 IgA (15 to 21 days)	3	78
23 IgA (22 to 35 days)	3	90
24 IgA (over 35 days)	1	23
25 Total antibodies (Ab) (all time points)	17	5339
27 Total antibodies (Ab) (1 to 7 days)	5	144
29 Total antibodies (Ab) (8 to 14 days)	6	247
30 Total antibodies (Ab) (15 to 21 days)	6	176
31 Total antibodies (Ab) (21 to 35 days)	4	19
32 Total antibodies (Ab) (over 35 days)	2	28
33 IgA/IgG (all time points)	2	775
34 IgA/IgG (1 to 7 days)	1	12
35 IgA/IgG (8 to 14 days)	1	10
36 IgA/IgG (15 to 21 days)	1	8
37 IgA/IgG (22 to 35 days)	1	1
38 IgA/IgM (all time points)	1	699
39 IgG in PCR+ve (all time points)	4	558
40 IgG in PCR +ve (1 to 7 days)	2	28
41 IgG in PCR+ve (8 to 14 days)	2	33
42 IgG in PCR+ve (15 to 21 days)	2	40
43 IgG in PCR‐ve (all time points)	6	252
44 IgG in PCR‐ve (1 to 7 days)	2	13
45 IgG in PCR‐ve (8 to 14 days)	3	30
46 IgG in PCR‐ve (15 to 21 days)	3	72
47 IgM in PCR+ve (all time points)	6	740
48 IgM in PCR+ve (1 to 7 days)	2	28
49 IgM in PCR+ve (8 to 14 days)	2	33
50 IgM in PCR+ve (15 to 21 days)	2	16
51 IgM in PCR‐ve (all time points)	8	352
52 IgM in PCR‐ve (1 to 7 days)	2	13
53 IgM in PCR‐ve (8 to 14 days)	3	30
54 IgM in PCR‐ve (15 to 21 days)	3	72
55 IgG/IgM in PCR+ve (all time points)	2	177
56 IgG/IgM in PCR+ve (1 to 7 days)	2	36
57 IgG/IgM in PCR+ve (8 to 14 days)	2	53
58 IgG/IgM in PCR+ve (15 to 21 days)	2	150
59 IgG/IgM in PCR‐ve (all time points)	4	215
60 IgG/IgM in PCR‐ve (1 to 7 days)	2	17
61 IgG/IgM in PCR‐ve (8 to 14 days)	3	40
62 IgG/IgM in PCR‐ve (15 to 21 days)	3	113
63 IgG (moderate)	1	44
64 IgG (severe)	1	52
65 IgG (critical)	1	37
66 IgM (moderate)	1	44
67 IgM (severe)	1	52
68 IgM (critical)	1	37
69 RT‐PCR (all time points ‐ throat)	2	276
70 RT‐PCR (1 to 7 days throat)	2	67
71 RT‐PCR (8 to 14 days ‐ throat)	2	142
72 RT‐PCR (15 to 21 days ‐ throat)	2	73
73 RT‐PCR (all time points ‐ sputum)	1	53
74 RT‐PCR (1 to 7 days ‐ sputum)	1	13
75 RT‐PCR (8 to 14 days ‐ sputum)	1	8
76 RT‐PCR (15 to 21 days ‐ sputum)	1	23

*Study characteristics*
Patient Sampling	2‐group study recruiting patients estimating sensitivity and specificity [1] Rt‐PCR confirmed COVID‐19 cases (n = 40) [2] Pre‐pandemic controls (n = 142) Recruitment: unclear Prospective or retrospective recruitment of cases: retrospective Sample size (virus/COVID cases): 182 (40) Inclusion and exclusion criteria: none stated
Patient characteristics and setting	Setting [1] Acute hospital samples (n = 16), recovering healthcare workers (n = 6), convalescent patients (n = 18) [2] Health blood donors (n = 60); organ donor samples (n = 50); pertussis vaccine study (BERT) (n = 32) Location [1] Acute hospital patients from Oxford University Hospitals NHS Foundation Trust (location of other groups NR) [2] National Health Service Blood and Transplant, UK National Quality in Organ Donation (QUOD) study, the ‘BERT’ study (A Study Exploring Whooping Cough Protection in Children and Adults), UK Country: UK Dates: [1] NR; [2] before December 2019 Symptoms and severity: [1] asymptomatic (n = 1); mild (n = 26); severe (n = 4); critical (n = 9) Sex: NR Age: [1] Median (range): 57 (22‐95) years; [2] NR Exposure history: NR
Index tests	Adams 2020 [A] is test [A] from the following entry: Test name: [A] ELISA test [B]‐[J] LFIA names withheld Manufacturer: [A] in‐house [B]‐[J] manufacturer name withheld Ab targets: [A] IgG and IgM [B]‐[C] total antibodies [D]‐[J] IgG and IgM Antigens used: [A] SARS‐CoV‐2 trimeric S protein [B]‐[J] details withheld Test method: [A] ELISA [B]‐[J] LFIA further details withheld Timing of samples: 4‐62 days after onset of symptoms Samples used: plasma Test operators: laboratory staff Definition of test positivity: [A]‐[J] NR Blinded to reference standard: NR Threshold predefined: no for [A], unclear for [B] to [J]
Target condition and reference standard(s)	Reference standard for cases: RT‐PCR Samples used: nose or throat swabs Timing of reference standard: NR Blinded to index test: yes Incorporated index test: no Reference standard for non‐cases: pre‐pandemic
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: computed from analysis of individual participant data All participants received the same reference standard: no Missing data: different tests were evaluted in different numbers of samples, no information on how sampling decisions were made Uninterpretable results: not mentioned Indeterminate results: not mentioned Unit of analysis: per patient
Comparative
Notes	Funding: NIHR, Oxford Biomedical Research Centre, the UK Government Department of Health and Social Care and grants from NIHR and the Medical Research Council Publication status: preprint (not peer reviewed) Source: medRxiv Study author COI: several authors declared relationships with companies for other work; funders were co‐authors
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	No
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	No
Could the conduct or interpretation of the index test have introduced bias?		High risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	No
Were all patients included in the analysis?	No
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		High risk

*Study characteristics*
Patient Sampling	See main entry for this study for characteristics and QUADAS‐2 assessment (Adams 2020 [A])
Patient characteristics and setting	See main entry for this study for characteristics and QUADAS‐2 assessment (Adams 2020 [A])
Index tests	Adams 2020 [B] is test [B] from the following entry: Test name: [A] ELISA test [B]‐[J] LFIA names withheld Manufacturer: [A] in‐house [B]‐[J] manufacturer name withheld Ab targets: [A] IgG and IgM [B]‐[C] total antibodies [D]‐[J] IgG and IgM Antigens used: [A] SARS‐CoV‐2 trimeric S protein [B]‐[J] details withheld Test method: [A] ELISA [B]‐[J] LFIA further details withheld Timing of samples: 4‐62 days after onset of symptoms Samples used: plasma Test operators: laboratory staff Definition of test positivity: [A]‐[J] NR Blinded to reference standard: NR Threshold predefined: no for [A], unclear for [B] to [J]
Target condition and reference standard(s)	See main entry for this study for characteristics and QUADAS‐2 assessment (Adams 2020 [A])
Flow and timing	See main entry for this study for characteristics and QUADAS‐2 assessment (Adams 2020 [A])
Comparative
Notes

*Study characteristics*
Patient Sampling	Multiple‐group study recruiting patients estimating sensitivity and specificity [1] Specimens from COVID‐19 cases recruited from 3 different sources (n = 157 specimens) [2] Specimens from non‐cases recruited from 13 different sources (n = 3308 specimens) Recruitment: unclear Prospective or retrospective recruitment of cases: unclear Sample size (virus/COVID cases): 3481 (3324) specimens Inclusion and exclusion criteria: none stated
Patient characteristics and setting	Setting: not described for most sample sets Location: not described for most sample sets Country: USA, China, but not described for most sample sets Dates: not described Symptoms and severity: not described Sex: not described Age: not described Exposure history: not described
Index tests	Test name: unnamed test Manufacturer: Premier Biotech, Minneapolis, USA (may be Hangzhou Alltest) Ab targets: IgG, IgM Antigens used: NR Test method: NR Timing of samples: NR Samples used: serum, plasma, fingerstick blood, venous whole blood (may be blood for majority of cases) Test operators: NR Definition of test positivity: NR Blinded to reference standard: no Threshold predefined: NR
Target condition and reference standard(s)	Reference standard for cases: various unclear, includes RT‐PCR‐pos Samples used: NR Timing of reference standard: NR Blinded to index test: yes Incorporated index test: serology tests were included in 1 cohort Reference standard for non‐cases: pre‐pandemic, RT‐PCR‐neg, healthy volunteers
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: no All participants received the same reference standard: no Missing data: none mentioned Uninterpretable results: none mentioned Indeterminate results: none mentioned Unit of analysis: specimens
Comparative
Notes	Funding: individual donors Publication status: preprint (not peer reviewed) Source: medRxiv Study author COI: none declared
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	No
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	No
If a threshold was used, was it pre‐specified?	Unclear
Could the conduct or interpretation of the index test have introduced bias?		High risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Unclear
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Unclear
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	No
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Unclear
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk

PERMALINK

Antibody tests for identification of current and past infection with SARS‐CoV‐2

Jonathan J Deeks

Jacqueline Dinnes

Yemisi Takwoingi

Clare Davenport

René Spijker

Sian Taylor-Phillips

Ada Adriano

Sophie Beese

Janine Dretzke

Lavinia Ferrante di Ruffano

Isobel M Harris

Malcolm J Price

Sabine Dittrich

Devy Emperador

Lotty Hooft

Mariska MG Leeflang

Ann Van den Bruel

Abstract

Background

Objectives

Search methods

Selection criteria

Data collection and analysis

Main results

Authors' conclusions

Plain language summary

Summary of findings

Summary of findings 1. What is the diagnostic accuracy of antibody tests, for the diagnosis of current or prior SARS‐CoV‐2 infection?

Background

Target condition being diagnosed

Index test(s)

Antibody tests

Clinical pathway

Prior test(s)

Alternative test(s)

Laboratory‐based molecular tests

Laboratory‐independent point‐of‐care and near‐patient molecular and antigen tests

Signs and symptoms

Routinely available biomarkers

Imaging tests

Rationale

Objectives

Secondary objectives

Methods

Criteria for considering studies for this review

Types of studies

Participants

Index tests

Target conditions

Reference standards

Search methods for identification of studies

Electronic searches

Cochrane COVID‐19 Study Register searches

COVID‐19 Living Evidence Database from the University of Bern

Searching other resources

Data collection and analysis

Selection of studies

Data extraction and management

Assessment of methodological quality

Statistical analysis and data synthesis

Investigations of heterogeneity

Sensitivity analyses

Assessment of reporting bias

Summary of findings

Updating

Results

Results of the search

1.

Description of included studies

1. Description of studies.

Participant characteristics

Study designs

Index tests

Methodological quality of included studies

2.

Participant selection

Index tests

Reference standards

Table A: World Health Organization guidelines for the diagnosis of SARS‐CoV‐2^a

*Study characteristics*
Patient Sampling	2‐group study to estimate sensitivity and specificity for detection of active disease [1] Laboratory‐confirmed COVID‐19 patients (n = 276) [2] Controls with other infections (n = 167). A third group of healthy controls was used to set thresholds (n = 200) but not estimate accuracy. Recruitment method: NR if patients were consecutive Sample size (viral/COVID cases): 443 (276) Exclusion criteria: none stated
Patient characteristics and setting	[1] Hospital (inpatients); Chongqing Three Gorges Central Hospital, Yongchuan Hospital Affiliated to Chongqing Medical University (CQMU), and The Public Health Center, in Chongqing, China (recruitment dates NR). 168/276 (61%) had fever. Median age 48 (IQR 37‐56; range 0‐84) years, 151/276 (55%) male. 99/276 (36%) reported known exposure  [2] Controls with other infection (n = 167); Second Hospital Affiliated to CQMU and Children’s Hospital Affiliated to CQMU; time NR. Other infections included: influenza A virus (25), respiratory syncytial virus (7), parainfluenza 111 virus (8), influenza B virus (5), adenovirus (6), Klebsiella pneumoniae (8), Streptococcus pneumoniae (3), Mycoplasma (5), Acinetobacter baumannii (10), Candida albicans (2), Staphylococcus aureus (3), Mycobacterium tuberculosis (4), Hepatitis B virus (33), Hepatitis C virus (22), Syphilis (23) and Saccharomycopsis (3) [3] Healthy controls (n = 200), source NR; recruited > 1 year before the outbreak. No further details
Index tests	1 Ab test, blinding NR Laboratory‐based in‐house luminescent immunoassay (CLIA) using serum samples Measured IgM +IgG. Antigen: peptide from SARS‐CoV‐2 S protein Test threshold: determined as the mean luminescence (CL) value of the 200 normal sera plus 5 folds of SD; cut‐off used ≥ 0.7 CL (for both IgG and IgM). (Determined in the healthy control group) Samples acquired day 2‐day 27 after symptoms. Person applying the test NR.
Target condition and reference standard(s)	1. Real time RT‐PCR detection of virus RNA, samples not described. Reference threshold and timing NR. Blinded to index test 2. Healthy controls, pre‐December 2019
Flow and timing	Time interval between index and reference: NR. Accuracy results were not disaggregated by time period since point of symptom onset. No missing data, uninterpretable or indeterminate results described Analysis participant‐based
Comparative
Notes	Funded by Emergency Project from the Science & Technology Commission of Chongqing; Major National S&T program grant from Science & Technology Commission of China; Grant from the National Natural Science Foundation of China, Grant from the Science & Technology Commission of Yuzhong district, Chongqing. COI (reported or derived): study author employed by BioScience Co. LTD, Tianjin, China Publication status (source): preprint (not peer reviewed) (medRxiv) NOTE: Study author institution reported as BioScience Co. LTD, Tianjin, China (www.bioscience‐tj.com/en/about.php)
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	No
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	No
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		High risk

*Study characteristics*
Patient Sampling	The report contains 3 different groups that fit with 2 different comparisons.  2‐group design with separate estimates of sensitivity and specificity  [1] COVID‐19‐positive patients in ICU (n = 30) [2] Healthy volunteers with negative RT‐PCR results (n = 30) Recruitment: unclear Sample size (virus/COVID cases): 60 (30) Inclusion and exclusion criteria: not further described  (Single group recruiting individuals presenting with symptoms extracted as Cassaniti 2020 (B))
Patient characteristics and setting	Setting: hospital inpatients (Infectious Diseases Unit or ICU, Tertiary hospital) Location: Fondazione IRCCS Policlinico San Matteo, Pavia Country: Italy Dates: NR Symptoms and severity: [1] NR [2] NR Sex: [1] 83% male (25/30); [2] 55% Male (11/30) Age: [1] median age, 73.5; range 38‐86 years; [2] median age, 38.5; range 25‐69 years) Exposure history: [1] NR; [2] 10 (33.3%) previously infected with common OC43, 229E, HKU1, and NL63 coronavirus
Index tests	Test name: VivaDiag COVID‐19 IgM/IgG Manufacturer: VivaChek Ab targets: IgM, IgG Antigens used: NR Test method: LFIA Timing of samples: [1] median 7 days (IQR 4‐11) after first test; [2] NR Samples used: serum or blood Test operators: NR Definition of test positivity: visible line Blinded to reference standard: unclear Threshold predefined: yes
Target condition and reference standard(s)	Reference standard for cases: RT‐PCR targeting RNA‐dependent RNA polymerase and E genes were used to detect the presence of SARS‐CoV‐2 according to the WHO guidelines (2 negatives required for non‐cases) Samples used: respiratory samples Timing of reference standard: [1] during patient care [2] unclear Blinded to index test: yes Incorporated index test: no
Flow and timing	Time interval between index and reference tests: no information Results presented by time period: no information All participants received the same reference standard: yes Missing data: none mentioned Uninterpretable results: none mentioned Indeterminate results: none mentioned Unit of analysis: participants
Comparative
Notes	Funding: VivaDiag COVID‐19 IgM/IgG Rapid Test provided free of charge by the Italian Chinese community. Regional Health Authority of Lombardy, Milan, Italy and Italian Ministry of Health, Ricerca Finalizzata Publication status: published letter Source: academic journal Study author COI: none mentioned
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	No
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		Unclear risk

*Study characteristics*
Patient Sampling	Single‐group study estimating sensitivity and specificity Patients presenting to A&E with fever and respiratory symptoms indicative of COVID‐19 infection. 2 additional cohorts extracted as separate 2‐group study (Cassaniti 2020 (A)) Recruitment: unclear Sample size (virus/COVID cases): 50 (38) Inclusion and exclusion criteria: NR
Patient characteristics and setting	Setting: A&E Location: Fondazione IRCCS Policlinico San Matteo, Pavia Country: Italy Dates: NR Symptoms and severity: NR Sex: 68% male 34 male/16 female Age: median age, 61.50; range 33‐97 years Exposure history: NR
Index tests	Test name: VivaDiag COVID‐19 IgM/IgG Manufacturer: VivaChek Ab targets: IgM, IgG Antigens used: NR Test method: LFIA Timing of samples: on presentation at A&E Samples used: serum or blood Test operators: NR Definition of test positivity: visible line Blinded to reference standard: yes on presentation Threshold predefined: yes
Target condition and reference standard(s)	Reference standard for cases: RT‐PCR targeting RNA‐dependent RNA polymerase and E genes were used to detect the presence of SARS‐CoV‐2 according to the WHO guidelines Samples used: nasal swab Timing of reference standard: on presentation Blinded to index test: yes Incorporated index test: no Reference standard for non‐cases: single negative RT‐PCR result
Flow and timing	Time interval between index and reference tests: done at the same time Results presented by time period: no (likely to be short as on admission) All participants received the same reference standard: yes Missing data: none mentioned Uninterpretable results: none mentioned Indeterminate results: not mentioned Unit of analysis: participants
Comparative
Notes	Funding: VivaDiag COVID‐19 IgM/IgG Rapid Test provided free of charge by the Italian Chinese community. Regional Health Authority of Lombardy, Milan, Italy and Italian Ministry of Health, Ricerca Finalizzata Publication status: published letter Source:Academic journal Study author COI: none mentioned
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Yes
Did the study avoid inappropriate inclusions?	Yes
Could the selection of patients have introduced bias?		Unclear risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	No
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		High risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		Unclear risk

*Study characteristics*
Patient Sampling	Unclear whether study recruited as 1 or 2 groups (we describe it as a 2‐group study), estimating sensitivity and specificity [1] RT–PCR‐positive samples, n = 7 samples [2] RT–PCR‐negative samples, but clinically suspicious for COVID‐19, n = 12 samples A 3rd group of 'normal' samples (n = 51), were used to derive test threshold and not included in the accuracy evaluation. Recruitment: unclear Prospective or retrospective recruitment of cases: unclear Sample size (virus/COVID cases): 19 (7) Inclusion and exclusion criteria: NR
Patient characteristics and setting	Setting: hospital samples Location: Guangzhou Eighth People’s Hospital and Nanfang Hospital, Guangzhou province Country: China Dates: NR Symptoms and severity: [1] NR; [2] fever: 12/12 (100%) Sex: NR Age: NR Exposure history: NR
Index tests	Test name: no name. LFIA that uses lanthanide‐doped polystyrene nanoparticles (LNPs) Manufacturer: in–house Ab targets: IgG Antigens used: recombinant nucleocapsid phosphoprotein of SARS‐CoV‐2 Test method: LFIA that uses lanthanide‐doped polystyrene nanoparticles (LNPs) Timing of samples: NR Samples used: serum Test operators: NR Definition of test positivity: At/Ac ratio (R) > 0.0666 Blinded to reference standard: NR Threshold predefined: defined from control samples
Target condition and reference standard(s)	Reference standard for cases: RT–PCR Samples used: NR Timing of reference standard: NR Blinded to index test: yes Incorporated index test: no Reference standard for non‐cases: RT–PCR single negative
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: NR All participants received the same reference standard: yes Missing data: none reported Uninterpretable results: none reported Indeterminate results: none reported Unit of analysis: sample
Comparative
Notes	Funding: National Natural Science Foundation of China and China Postdoctoral Science Foundation Publication status: peer–reviewed early online Source: academic journal Study author COI: study authors state no competing financial interests
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	Unclear
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	No
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		High risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk

*Study characteristics*
Patient Sampling	Single group estimating sensitivity in convalescent patients [1] Hospital COVID‐19 convalescent patients (n = 60) Recruitment: unclear Sample size (virus/COVID cases): 60 (60) Inclusion and exclusion criteria: NR
Patient characteristics and setting	Setting: hospital inpatients (convalescent) Location: Wuhan Tongji Hospital Country: China Dates: admitted 12 January 2020‐5 February 2020 Symptoms and severity: no information Sex: no information Age: no information Exposure history: no information
Index tests	Test name: NR Manufacturer: NR Ab targets: IgM, IgG Antigens used: NR Test method: NR but presumed to be CLIA based on reported threshold in AU/mL Timing of samples: during hospital stay (between 3 March 2020 and 14 March 2020) Samples used: NR Test operators: unclear Definition of test positivity: > 10 AU/mL Blinded to reference standard: unclear Threshold predefined: yes
Target condition and reference standard(s)	Reference standard for cases (including threshold): method NR Samples used: NR Timing of reference standard: diagnosed during initial hospital stay (6‐7 weeks previously) Blinded to index test: yes Incorporated index test: no
Flow and timing	Time interval between index and reference tests: 6‐7 weeks Results presented by time period: results presented by day since onset All participants received the same reference standard: presumed Missing data: none mentioned Uninterpretable results: none mentioned Indeterminate results: none mentioned Unit of analysis: participant
Comparative
Notes	Funding: Beijing Natural Science Foundation Publication status: published letter Source: academic journal Study author COI: none mentioned
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Yes
Did the study avoid inappropriate inclusions?	Yes
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	No
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		High risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Unclear
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Unclear
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		Unclear risk

*Study characteristics*
Patient Sampling	Single‐group study recruiting patients estimating sensitivity [1] confirmed COVID‐19 cases Recruitment: consecutive (inferred). From all confirmed cases admitted to hospital Prospective or retrospective recruitment of cases: retrospectively (appears) Sample size (virus/COVID cases): 22 participants (corresponding to 37 samples) Inclusion and exclusion criteria: not clearly defined; describes all participants having typical ground‐glass opacity of the lung on CT but not clear if this was part of eligibility
Patient characteristics and setting	Setting: hospital inpatient Location: Fifth Hospital of Shijiazhuang Country: China Dates: from 21 January‐24 February 2020 Symptoms and severity: typical ground‐glass opacity in lung was observed in CT scan results of all participants. At the time the paper was written all participants had recovered and been discharged from hospital. Sex: 14/22 male (64%) Age: 40 (4‐72) years Exposure history: 11 participants had recent history of travel to epidemic areas, and the remaining 10 had close contacts with their family members, who were confirmed to be infected by 2019‐nCoV
Index tests	Gao 2020b [A] is test [A] from the following entry: Test name: [A] CLIA; [B] GICA; [C] ELISA Manufacturer: Beier Bioengineering Company (Beijing, China) Ab targets: IgG and IgM Antigens used: spike (S) and nucleocapsid (N) proteins of 2019‐nCoV Test method: [A] CLIA; [B] GICA; [C] ELISA Timing of samples: [1] early stage (1‐7 days pso) 10/37 samples (27%), [2] middle stage (8‐14 days pso) 13/37 samples (35%); [3] late stage (14‐24 days pso) 14/37 samples (38%) Samples used: serum Test operators: laboratory staff Definition of test positivity: [A] samples with an concentration ≥ 8 arbitrary unit (AU)/mL were considered positive. [B] Visible line. [C] The absorbance at 450 nm (A450 nm) of each well was determined and the cut‐off value was 0.10+Anegative control. A value > cut‐off value was considered a positive result. Blinded to reference standard: NR Threshold predefined: [A] samples with an concentration ≥ 8 arbitrary unit (AU)/mL were considered positive. [B] Positive results showed the appearance of both control line and testing line. [C] The absorbance at 450 nm (A450 nm) of each well was determined and the cut‐off value was 0.10+Anegative control. A value > cut‐off value was considered a positive result.
Target condition and reference standard(s)	Reference standard for cases: RT‐PCR assay (2019‐nCoV RNA Test Kit, Daan Gene Company, China) Samples used: nasal and pharyngeal swab specimens Timing of reference standard: on admission (most likely) Blinded to index test: yes, index tests performed on already‐confirmed cases (inferred) Incorporated index test: no Reference standard for non‐cases: N/A
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: yes All participants received the same reference standard: yes Missing data: timing of reference standard test Uninterpretable results: Indeterminate results: Unit of analysis: samples
Comparative
Notes	Funding: NR Publication status: published letter Source: Chinese Medical Journal Study author COI: none
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	Unclear
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk

*Study characteristics*
Patient Sampling	3‐group study estimating sensitivity and specificity [1] COVID‐19 patients (n = 55) [2] Pre‐pandemic healthy controls (n = 45) Third group of patients admitted with a clinical and radiological diagnosis of pneumonia of unknown etiology but RT‐PCR‐negative reported as Garcia 2020 (B) Recruitment: NR Sample size (virus/COVID cases): 100 (55) Inclusion and exclusion criteria: NR
Patient characteristics and setting	Setting: [1] hospital inpatient [2] pre‐pandemic controls Location: [1] Hospital Universitario Príncipe de Asturias, Madrid [2] Hospital Universitario Príncipe de Asturias Country: Spain Dates: [1] 1 March‐6 April 2020 [2] 1 October‐30 November 2019 Symptoms and severity: NR Sex: [1] male n = 33, 60% [2] male n = 27, 60% Age: [1] median age 63, IQR 50‐79 [2] median age 55, IQR 34‐66 Exposure history: NR
Index tests	Test name: AllTest COV‐19 IgG / IgM kit Manufacturer: AllTest Biotech, Hangzhou, China Ab targets: IgM, IgG Antigens used: NR Test method: immunochromatography Timing of samples: days 0‐14+ pso Samples used: serum Test operators: laboratory staff Definition of test positivity: visible line Blinded to reference standard: no Threshold predefined: yes
Target condition and reference standard(s)	Reference standard for cases: RT‐PCR Samples used: NR Timing of reference standard: NR Blinded to index test: yes Incorporated index test: no
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: yes: < 7 days 15% (n = 8); 7‐13 days 44% (n = 24); ≥ 14 days 42% (n = 23) All participants received the same reference standard: no Missing data: NR Uninterpretable results: NR Indeterminate results: NR Unit of analysis: participants
Comparative
Notes	Funding: no funding received Publication status: preprint (not peer reviewed) Source: medRxiv Study author COI: none declared
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	Unclear
Did the study avoid inappropriate exclusions?	Yes
Did the study avoid inappropriate inclusions?	Unclear
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		Low risk

*Study characteristics*
Patient Sampling	4‐group study to estimate sensitivity and specificity for diagnosing active disease. [1] Hospitalised COVID‐19 patients (51; 161 samples) [2] Pre‐pandemic sera (491) Recruitment: NR (appears retrospective); consecutive or otherwise NR Review team excluded: [3] Blood donors during pandemic (200) [4] Cohort of 209 pauci‐symptomatic suspected cases (mild signs compatible with COVID‐19 ‐fever, cough or dyspnea) who had been in contact with a confirmed case as no reference standard reported
Patient characteristics and setting	Setting: inpatient Location: Hôpital Bichat, Paris Country: France Dates: NR
Index tests	This entry (Grzelak 2020 [A]) refers to test [A] in the list below: 5 tests evaluated: A. LIPS (S1 protein) B. LIPS (N protein) C. ELISA (N protein) D. S‐Flow (unknown) E. ELISA tri‐S (S protein) Manufacturer: in‐house Ab targets: A. total Ab; B. total Ab; C. IgG; D IgM or IgG; E. total Ab Antigens used: A. S1; B. N‐based; C. full‐length SARS‐CoV‐2 N protein; D. S at the cell surface; E. trimeric S (recombinant S glycoprotein ectodomain)
Target condition and reference standard(s)	Reference standard for cases: NR. Described as confirmed COVID‐19 hospitalised cases only Samples used: not described Timing of reference standard: not described Was it blind to index test: not described
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: no All participants received the same reference standard: no Missing data: pre‐pandemic sera are missing from the evaluations of ELISA tri‐S (n = 391), S‐flow (n = 357) and LIPS S1 and N (n = 2) Sample‐based analysis
Comparative
Notes	Funding: OS lab is funded by Institut Pasteur, ANRS, Sidaction, the Vaccine Research Institute (ANR‐ 10‐LABX‐77), Labex IBEID (ANR‐10‐LABX‐62 IBEID), “TIMTAMDEN” ANR‐14‐CE14‐0029, “CHIKV‐Viro‐ Immuno” ANR‐14‐CE14‐0015‐01 and the Gilead HIV cure program. LG is supported by the French Ministry of Higher Education, Research and Innovation.ME lab is funded by Institut Pasteur, Labex IBEID (ANR‐10‐LABX‐62‐IBEID), Reacting, EU grant Recover, ANR Oh’ticks. HM received core grants from the G5 Institut Pasteur Program, the Milieu Intérieur Program (ANR‐10‐LABX‐69‐01) and INSERM. C.P. is supported by a fellowship from the Agence Nationale de Recherches sur le Sida et les Hépatites Virales (ANRS). SVDW lab is funded by Institut Pasteur, CNRS, Université de Paris, Santé publique France, Labex IBEID (ANR‐10‐LABX‐62‐IBEID), REACTing, EU grant Recover. Publication status: preprint Source: medRxiv Study author COI: PC is the founder and CSO of TheraVectys
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	Unclear
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	No
Could the conduct or interpretation of the index test have introduced bias?		High risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Unclear
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Unclear
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	No
Were all patients included in the analysis?	No
Did all participants receive a reference standard?	Yes
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk

*Study characteristics*
Patient Sampling	2‐group study estimating sensitivity and specificity for detection of active disease in people with suspected or confirmed SARS‐Cov‐2 infection and other infection controls. 1. Cases ‐ 101 inpatients from Wuhan (43 PCR confirmed and 58 probable) provided 169 paired throat and blood samples (69 from confirmed and 100 from probable) 2. Cases ‐ 39 inpatient confirmed cases from Beijing provided 39 samples (total of 208 samples) 3. Control samples provided by people with acute LRTI (135) Family cluster also recruited but does not contribute data. Healthy individuals (150) used to define threshold. Additional plasma samples positive for human CoV‐229E, ‐NL63, ‐OC43, ‐HKU1, and SARS‐CoV previously obtained were included for Western Blot cross‐reactivity analysis. Recruitment method NR
Patient characteristics and setting	1. Inpatients at Wuhan hospitals. 43 confirmed cases (PCR or deep sequencing): 20 severe; 23 mild to moderate; 58 possible cases (test‐negative but with clinical signs, X‐ray evidence): 5 severe, 53 mild to moderate. Exposure history NR 2. Beijing hospitals, China (recruitment dates January 2020); 8 severe and 31 mild to moderate. No further details 3. Acute LRTI infection controls: 135 samples from adult patients. No further detail (Family cluster of 6; aged 2‐64, 3 male 3 female. Healthy control samples from Wuhan City adult health check‐ups, 2018‐19)
Index tests	3 ELISA assays, blinding NR In‐house ELISA (indirect, laboratory‐based, using blood/plasma samples. Measured IgM, IgA, IgG. Antigen: rNPs (recombinant N protein) from SARS‐CoV‐2 virus Test threshold determined from mean values and SD of healthy individual plasma (calculated the mean absorbance at 450 nm (A450) of the negative sera plus 3 folds of the SD values which were 0.13, 0.1 and 0.30 for IgM, IgA, and IgG, respectively. Samples acquired 1‐39 days after disease onset (41/208 at 1‐7 days; 84/208 at 8‐14 days; 83 > 14 days pso). Person applying the test not described
Target condition and reference standard(s)	1. and 2. Confirmed cases ‐ deep sequencing or a qPCR assay with a detection limit of 1 copy/μL, using throat swabs samples. Positivity threshold: NR. Probable cases ‐ clinical manifestation, chest radiography imaging and epidemiology but no virus detected by deep sequencing or qPCR. Timing NR. Not blinded to index test. 3. LRTI controls: pre‐pandemic samples (2018‐2019)
Flow and timing	Differential verification: all cases had RT‐PCR but some were negative, plus controls did not have RT‐PCR. Time interval between index and reference: presumed short. There are multiple samples for some participants (cases) but others contribute only sample with a range of days pso; only data for 1‐7 days pso can be disaggregated from the rest. Missing data, uninterpretable and indeterminate results not described Per participant and per sample data can be extracted
Comparative
Notes	Funded by Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Sciences, Non‐profit Central Research Institute Fund of CAMS, National Major Science & Technology Project for Control and Prevention of Major Infectious Diseases in China. No conflicts of interest reported Publication status: preprint
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	No
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		Unclear risk

*Study characteristics*
Patient Sampling	Single‐group study to estimate sensitivity for detecting active or prior infection Confirmed COVID‐19 patients (211) Recruitment: NR; likely retrospective. Consecutive or otherwise NR
Patient characteristics and setting	Setting: inpatient Location: Chongqing Three Gorges Central Hospital, Chongqing. Country: China Dates: 23 January‐3 March
Index tests	Test name: Magnetic Chemiluminescence Enzyme Immunoassay (MCLIA) kit Manufacturer: Bioscience Co., Ltd (Chongqing, China) Ab targets: IgM, IgG Antigens used: N and S (nucleoprotein and a peptide from the SARS SARS‐CoVCoV‐2 S protein)
Target condition and reference standard(s)	Reference standard for cases: Chinese CDC guidelines (Trial Version 6); included RT‐PCR Samples used: NR Timing of reference standard: unclear; appears that repeat PCR undertaken during hospitalisation; 74/211 met discharge criteria during study period (normal temperature, significantly improving respiratory symptoms and chest radiology plus 2 repeat negative PCRs with ≥ 1‐day interval) Was it blind to index test: unclear
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: yes All participants received the same reference standard: yes Missing data: none described; however text states 993 samples but only 409 reported for IgM and 507 for IgG Uninterpretable results: none described
Comparative
Notes	Funding: funded by Chongqing Education Board “new coronavirus infection and prevention” emergency scientific research project (KYYJ202006YYJ202006). Chongqing Science and Technology Bureau “new crown pneumonia epidemic emergency science and technology special” the fourth batch of projects. Famous teacher project of Chongqing talent plan Publication status: preprint Source: medRxiv Study author COI: none declared
*Methodological quality*
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	Unclear
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
The reference standard does not incorporate the index test	Unclear
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		Unclear risk