Nagasawa 2020 [A].

Study characteristics
Patient Sampling	Purpose: Detection of anti‐SARS‐CoV‐2 IgG and IgM antibodies in COVID‐19 patients, diagnosis of current acute‐phase infection or current convalescent‐phase infection Design: Multi‐group study to estimate sensitivity and specificity [1] Confirmed COVID patients (45 samples from 26 patients) [1a] Moderate COVID patients (n = 19) [1b] Severe COVID patients (n = 7) [2] Controls, not eligible for our review Recruitment: Not stated. [1] Inpatients at Musashino Red Cross Hospital, Musashino City, Tokyo, Japan, admitted between April 12 and May 8 2020 Prospective or retrospective: Unclear Sample size: 57 (45) of which 45 (45) were eligible for our review Further detail: [1] Inclusion: Patients who were diagnosed as COVID‐19 from positive RT‐PCR test for SARS‐CoV‐2 by using naso‐pharynx swab specimens and admitted in our hospital between April 12 and May 8, 2020 Exclusion criteria not stated
Patient characteristics and setting	Setting: Hospital inpatients Location: Musashino Red Cross Hospital, Musashino City, Tokyo, Japan Country: Japan Dates: April 12 to May 8 2020 Symptoms and severity: [1a] Moderate COVID patients (n = 19) [1b] Severe COVID patients (n = 7) 26 confirmed pneumonia, 7 confirmed ventilator usage, 1 death. Demographics: 14 male, 12 female Age 19‐82 years, mean 52.6 (SD 6.3) Exposure history: Not stated Non‐Covid group 1: NA
Index tests	Test name: [A] 2019‐nCoV Ab Test [B] COVID‐19 IgG/IgM Rapid Cassette Test [C] 2019‐nCoV IgG/IgM Rapid Test Casette Manufacturer: [A] INNOVITA Biological Technology Co., China [B] Zhejiang Orient Gene Biotech Co., China [C] Hangzhou AllTest Biotech Co., China Antibody: [A] IgG/IgM [B] IgG/IgM [C] IgG/IgM Antigen target: [A], [B], [C] Unclear Evaluation setting: Laboratory Test method: [A] [B] [C] Described in paper as ELISAs, but also as rapid tests; the test names matched available rapid tests and have been included in review as rapid tests. Timing of samples: 1‐29 days pso 1‐5 days pso: 1/45 6‐10 days pso: 10/45 11‐15 days pso: 19/45 16‐20 days pso: 9/45 21‐29 days pso: 6/45 Samples used: serum Test operator: Unclear, laboratory staff? Clinical staff? Result confirmed by at least two inspectors Definition of test positivity: Not stated. (Test was performed according to the protocol of each manufacturer. The result was confirmed by at least two inspectors and adopted only in case with unanimous decision) Blinding reported: Not stated Threshold predefined: yes, according to the protocol of each manufacturer
Target condition and reference standard(s)	Reference standard: RT‐PCR performed at SRL laboratory (Tokyo, Japan); threshold not stated Samples used: naso‐pharynx swab specimens Timing of reference standard: Not stated Blinded to index test: Yes Incorporated index test: No Definition of non‐COVID cases: NA Samples used: NA Timing of reference standard: NA Blinded to index test: NA Incorporated index test: NA
Flow and timing	Time interval between index and reference tests: Unclear All patients received same reference standard: Yes Missing data: Yes As in F1: samples missing for test [B] days 1‐5, test [A] days 11‐15, test [B] 11‐15 days IgG Uninterpretable results: Not stated Indeterminate results: Not stated Unit of analysis: Samples
Comparative
Notes	Funding: Test kits provided by SoftBank Cooperation (Tokyo, Japan) Publication status: Published paper Source: SN Comprehensive Clinical Medicine Author COI: Authors declared no conflict of interest.
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?	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?	Yes
Did all participants receive a reference standard?	No
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk