Fenwick 2021 [A].

Study characteristics
Patient Sampling	Purpose: Diagnosis of current acute/sub‐acute‐phase infection Design: Two‐group study to estimate sensitivity and specificity [1] Confirmed COVID patients (93 sera) [2] Non‐COVID samples (n = 65); pre‐pandemic including 18 samples from patients documented positive for a human coronavirus (E229, OC43, HKU1, or NL63) RT‐PCR Recruitment: Not stated Prospective or retrospective: Retrospective Sample size: 158 (93) Further detail: Not stated
Patient characteristics and setting	Setting: [1] Hospital inpatients Location: Not stated (Lausanne University Hospital, Lausanne?) Country: Switzerland Dates: Not stated Symptoms and severity: Hospitalised patients with severe‐to‐moderate symptoms Demographics: Not stated Exposure history: Not stated Non‐Covid group 1: [2] Pre‐pandemic Source: Sampled before November 2019, source not stated Characteristics: 18/65 samples from patients documented positive for a human coronavirus (E229, OC43, HKU1, or NL63) RT‐PCR. Part of the diverse set of 108 patient sera used for study 2 (which included an additional 43 pre‐pandemic patient samples). This diverse set of 108 samples consisted of sera from pregnant women (n = 14), pre‐pandemic coronavirus‐infected donors (OC43, E229, NL63, and HKU1; n = 19), patients with infectious diseases (HIV, rubella, HSV1, HSV2, RSV, CMV, EBV, influenza, and varicella; (n = 57)), and patients with auto‐immune diseases, including lupus (n = 18).
Index tests	Test name: [A] Not stated [B] Not stated [C] LIAISON SARS‐CoV‐2 IgG kit [D] MAGLUMI 2019‐nCoV IgG and IgM kits [E] Elecsys anti‐SARS‐CoV‐2 assay Manufacturer: [A] Euroimmun [B] Epitope Diagnostis [C] Diasorin [D] Snibe [E] Roche Antibody: [A] IgG [B] IgG [C] IgG [D] IgG [E] pan‐Ig Antigen target: [A] S1‐protein [B] N‐protein [C] S1‐protein [D] N‐protein and S antigen peptide (the Snibe assay was grouped with the N‐protein assays in our analysis since it contained only a portion of the S1‐protein) [E] N‐protein Evaluation setting: [A] Lab test performed in lab [B] Lab test performed in lab [C] Lab test performed in lab [D] Lab test performed in lab [E] Lab test performed in lab Test method: [A] ELISA [B] ELISA [C] CLIA [D] CLIA [E] ECLIA Timing of samples: 0 to 33 days post‐onset of the symptoms: 0‐5 days pso: 8/93 6‐10 days pso: 19/93 11‐15 days pso: 37/93 16‐33 days pso: 29/93 Samples used: Serum Test operator: Service of Immunology and Allergy and Service of Microbiology at the Lausanne University Hospital Definition of test positivity: Not stated Blinding reported: Unclear Threshold predefined: ELISA and CLIA were performed according to the manufacturers’ instructions. Optical densities (OD) were measured with a microplate reader (800 TSI, BioTek, USA). Each sample was measured in duplicate.
Target condition and reference standard(s)	Reference standard: SARS‐CoV‐2 PCR, threshold not stated Samples used: Not stated Timing of reference standard: Not stated Blinded to index test: yes, prior index test Incorporated index test: no Definition of non‐COVID cases: Pre‐pandemic Samples used: Pre‐pandemic Timing of reference standard: Before November 2019 Blinded to index test: yes, prior index test Incorporated index test: no
Flow and timing	Time interval between index and reference tests: Not stated All patients received same reference standard: No Missing data: Small differences in the number of sera tested across assays were due to the insufficient volume of some samples. [A] 89/93 COVID samples [B] 90/93 COVID samples Uninterpretable results: Not stated Indeterminate results: Not stated (according to Figure 4, there must have been intermediate results for tests [A], [B] and [C]) Unit of analysis: Not stated
Comparative
Notes	Funding: Funding for this project was provided through the Lausanne University Hospital, through the Swiss Vaccine Research Institute and through the Coronavirus Accelerated R&D in Europe (CARE) IMI project. Publication status: Published paper Source: Journal of Virology Author COI: Not stated
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?	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?	Unclear
Could the patient flow have introduced bias?		High risk