Nicol 2020 [A].

Study characteristics
Patient Sampling	Purpose: The aim of the study was to assess the clinical performance of CE marked assays available in Europe to detect SARS‐CoV‐2 antibodies: two automated immunoassays (Euroimmun and Abbott assays) targeting two different proteins and also one lateral flow immunoassay (NG Biotech). Multi‐group study to estimate sensitivity and specificity for diagnosis of active disease Design: [1] patients with RT‐PCR‐confirmed SARS‐CoV‐2 infection (n = 82 patients, 141 samples) [2] patients with symptoms consistent with COVID‐19 but RT‐PCR‐negative (clinical diagnosis of pneumonia of unknown aetiology) (n = 52 patients, 57 samples) [3] Pre‐pandemic control group specimens (n = 50 samples) [4] Samples with pathogen potentially cross‐reactive with SARS‐CoV‐2 (n = 25 samples) [5] Samples from pregnant women (n = 10) [6] Samples from patients with positive rheumatoid factor (n = 10) Groups [4] to [6] combined Recruitment: Samples were collected in the virology laboratory of Angers University Hospital, France Prospective or retrospective: Retrospective Sample size: Individuals: 229 (82) Samples: 293 (141) Further detail: Not stated
Patient characteristics and setting	Setting: [1] Not stated Location: [1] Virology laboratory of Angers University Hospital, France Country: [1] France Dates: Not stated Symptoms and severity: [1] Not stated Demographics: [1] median age: 67 years Exposure history: [1] Not stated Non‐Covid group 1: [2] Pneumonia of unknown aetiology, RT‐PCR‐negative Source: [2] Virology laboratory of Angers University Hospital, France Characteristics: [2] median age: 64 years Non‐Covid group 2: [3] Pre‐pandemic controls [4] Cross‐reactivity samples [5] Pregnant women [6] Patients with rheumatoid factor (RF) Source: [3] March 2019, Virology laboratory of Angers University Hospital, France [4]‐[6] Not stated Characteristics: [3] Not stated [4] Seasonal coronaviruses n = 2, influenza A virus n = 3, respiratory syncytial virus n = 3, rhinovirus n = 3, parainfluenzae virus n = 1, acute EBV infection (positive for EBV VCA IgM and EBV VCA IgG) n = 7, acute CMV infection (positive for CMV IgM) n = 1, M. pneumonia infection n = 2, acute Hepatitis A infection n = 1, acute hepatitis E infection n = 2 [5] Pregnant women [6] Rheumatoid factor
Index tests	Test name: [A] Abbott SARS‐CoV‐2 CLIA IgG assay [B] to [D] Euroimmun Anti‐SARS‐CoV‐2 ELISA IgG/IgA assays [E] LFIA NG‐Test® IgG‐IgM COVID‐19 Manufacturer: [A] Abbott Diagnostics, IL, USA [B] to [D] Euroimmun, Lübeck, Germany [E] NG Biotech Laboratoires, Guipry‐ Messac, France Antibody: [A] IgG [B] IgG [C] IgG or IgA [D] IgA [E] IgG, IgM Antigen target: [A] SARS‐CoV‐2 nucleoprotein (NP) [B] to [D] recombinant S1 structural protein ‐ assay detects antibodies against the viral spike‐protein [E] SARS‐CoV‐2 nucleoprotein Evaluation setting: [A] Laboratory, used in laboratory [B] to [D] Laboratory, used in laboratory [E] POC, used in laboratory Test method: [A] CLIA assay [B] to [D] ELISA [E] Lateral flow immunoassay (colloidal gold) (CGIA) Timing of samples: [A]‐[C] 0‐> 15 days after onset of symptoms 0‐7 days pso 32/141 8‐14 days pso 29/141 15+ days pso 80/141 [2] median time between symptom onset and sera: 9.5 days 0‐7 days pso 24/57 8‐14 days pso 15/57 15+ days pso 18/57 Samples used: [A]‐[C] Serum Test operator: [A]‐[C] Laboratory personnel Definition of test positivity: [A] cut‐off for positivity = ratio ≥ 1.4 [B] cut‐off for positivity = ratio ≥ 1.1; cut‐off for negativity = ratio < 0.8 [C] Visible lines Blinding reported: [A]‐[C] Unclear Threshold predefined: [A] Yes ‐ "performed according to the manufacturer’s instructions" [B] Yes ‐ "performed according to the manufacturer’s instructions" [C] Yes, visible lines
Target condition and reference standard(s)	Reference standard: [1] RT‐PCR Samples used: [1] Not reported Timing of reference standard: [1] Not reported Blinded to index test: [1] Yes, prior Incorporated index test: [1] No Definition of non‐COVID cases: [2] RT‐PCR for pneumonia PCR‐negative controls [3] pre‐pandemic [4]‐[6] None (no RT‐PCR detection performed) Samples used: [2] Not stated [3] Pre‐pandemic [4]‐[6] not tested Timing of reference standard: [2] Not stated [3] Pre‐pandemic [4]‐[6] not tested Blinded to index test: [2]‐[6] All prior to index test Incorporated index test: [2]‐[6] No
Flow and timing	Time interval between index and reference tests: Unclear All patients received same reference standard: No Missing data: To determine the specificity for IgG of the three assays, we excluded two specimens positive for serological assays but negative for RT‐PCR because the symptoms were strongly compatible with the COVID‐19 and RT‐PCR was performed 17–24 days after symptom onset. Uninterpretable results: Not stated Indeterminate results: [C] CLIA ‐ "Grey zone was considered positive for the statistical analyses." Unit of analysis: Samples
Comparative
Notes	Funding: This research did not receive any specific grant from funding agencies. NG‐Test® IgG‐IgM COVID‐19 rapid test cassettes (NG Biotech Laboratoires) were kindly provided by the manufacturer. Publication status: Published paper Source: Journal of Clinical Virology Author COI: The authors declared that they had 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?	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?			Unclear
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?	No
Were all patients included in the analysis?	No
Did all participants receive a reference standard?	No
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk