Bond 2020.

Study characteristics
Patient Sampling	Purpose: Diagnostic performance evaluation for multiple COVID‐19 tests Design: Multi‐group study estimating both sensitivity and specificity. [1A] Symptomatic RT‐PCR confirmed COVID‐19 cases (n = 91 patients) [1B] Symptomatic COVID‐19‐negative on single RT‐PCR (n = 1217 patients) [2] Pre‐pandemic controls obtained in 2018 (n = 56 patients) Group 1B only used to assess specificity for one test Recruitment: Unclear Prospective or retrospective: Retrospective Sample size: 1400 (91) Note: the total sample size reported above only applied to one test, for which sera from 1217 COVID‐19 negative subjects were used to further assess specificity. Further detail: No more details available
Patient characteristics and setting	Setting: Both in‐ or outpatients. All serum samples were collected in a tertiary hospital or a state reference laboratory; mild cases were not hospitalised. Location: Royal Melbourne Hospital and Victorian Infectious Diseases Reference Laboratory Country: Australia Dates: Dates not reported but likely collected in the first semester of 2020 Symptoms and severity: 71 mild (not hospitalised), 17 moderate (hospitalised, non‐ICU) and 3 severe cases (ICU). Demographics: Not stated Exposure history: Not stated Non‐Covid group 1: Group [1B] symptomatic COVID‐19 negative Source: Subjects presenting to the hospital emergency department between Feb 6th and Apr 15th, 2020 Characteristics: Not stated Non‐Covid group 2: Group [2] ‐ 56 pre‐pandemic controls obtained in 2018 Source: Pre‐pandemic specimens collected in 2018 Characteristics: Not stated
Index tests	Study evaluated multiple assays; timing pso provided only for one of them; remainder were excluded Test name: EUROIMMUN Anti‐SARS‐CoV‐2 ELISA (IgA or IgG) [Assays from [A] CTK Biotech Inc. (China), [B] VivaChek Biotech (Hangzhou) Co. Ltd. (China), [C] Hangzhou Alltest Biotech Co. Ltd. (China), [D] Guangzhou Wondfo Biotech Co. Ltd. (China), [E] Hightop Biotech (China) all excluded] Manufacturer: [F] & [G] EUROIMMUN AG Manufacturer: EUROIMMUN AG Antibody: IgA or IgG Antigen target: S1 domain of the spike‐protein Evaluation setting: lab test, done in lab Test method: Enzyme‐Linked Immunosorbent Assay (ELISA) Timing of samples: Any time point (229 samples); > 14 days (157 samples) Samples used: Serum Test operator: Not stated Threshold: ratio < 0.8, negative result; (2) ratio ≥ 0.8 to < 1.1, borderline result; and (3) ratio ≥ 1.1, positive result Blinding reported: Not stated Threshold predefined: Yes, as per manufacturer
Target condition and reference standard(s)	Group [1A]: Coronavirus Typing Assay (AusDiagnostics) followed by an unspecified confirmatory test at the state reference laboratory Samples used: Upper and/or lower respiratory tract specimens Timing of reference standard: Not stated but likely done before index test Blinded to index test: Not stated Incorporated index test: No Definition of non‐COVID cases: Group [1B]: Single negative RT‐PCR Group [3]: no testing, pre‐pandemic sera 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: Not stated All patients received same reference standard: No Missing data: Unclear Uninterpretable results: Unclear Indeterminate results: Unclear
Comparative
Notes	Funding: Work supported by a grant from the NHMRC Medical Research Future Fund. Some authors are recipients of the following: Investigator Grant from the National Health and Medical Research Council (NHMRC) of Australia; NHMRC Practitioner Fellowship; NHMRC Postgraduate Scholarship. Publication status: Published article Source: Academic journal 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?	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?			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?	Unclear
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?	Unclear
Did all participants receive a reference standard?	No
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk