Fujigaki 2020 [A].

Study characteristics
Patient Sampling	Purpose: Assessment of clinical performance of three antibody tests for identification of acute and convalescent‐phase SARS‐CoV‐2 infection Design: Single‐group study estimating sensitivity: residual samples from PCR‐confirmed COVID‐19 patients (n = 29, providing 99 samples) Recruitment: Unclear Prospective or retrospective: Retrospective Sample size: 29 (29) Further detail: No more details available
Patient characteristics and setting	Setting: Inpatient setting (all hospitalised) Location: Fujita Health University Hospital,Toyoake, Aichi Country: Japan Dates: 28 February to 15 April 2020 Symptoms and severity: Not stated (however, all patients were hospitalised, so likely had symptoms) Demographics: Mean age 52.9 y (SD 21.9); 14, 48% male Exposure history: Not stated
Index tests	Test name: [A] 2019‐nCoV IgG/IgM Rapid Test Cassette [B] COVID‐19 IgM/IgG Duo [C] 2019‐nCoV IgG/IgM Detection Kit Manufacturer: [A] Hangzhou AllTest Biotech Co., Ltd., China [B] SD BIOSENSOR, Korea [C] Vazyme Biotech Co., Ltd., China Antibody: All tests: IgM, IgG Antigen target: All tests: Unclear Evaluation setting: All tests: POC tests, likely done in lab (samples were residual and had been frozen) Test method: All tests: Lateral flow immunoassay ‐ colloidal gold (CGIA) Timing of samples: Day 0 to 35; day 0‐7: 18 patients; 27 samples day 8‐14: 22 patients; 39 samples day 15‐21 18 patients; 28 samples day > 21 4 patients; 5 samples Samples used: Serum (residual and frozen prior to testing) Test operator: Not stated Definition of test positivity: As per manufacturer: visual‐based Blinding reported: Not stated Threshold predefined: Yes, visual‐based
Target condition and reference standard(s)	Reference standard: RT‐PCR test (no more details available) Samples used: Nasopharyngeal swabs Timing of reference standard: At the time or prior to hospital admission (not further specified) Blinded to index test: Yes (done earlier) Incorporated index test: No
Flow and timing	Time interval between index and reference tests: Not stated All patients received same reference standard: Yes, although different RT‐PCR assays could have been used. Missing data: None reported; some participants provided only one sample while others provided up to 12. Uninterpretable results: None reported Indeterminate results: None reported Unit of analysis: Presented per sample in the paper; extracted on a per patient basis by review team using Fig 1 and Fig 2 and including one sample per patient per week post‐symptom onset (any positive result over‐rode negative results in same week)
Comparative
Notes	Funding: No funding reported Nichirei Biosciences Inc. and Shionogi & Co., Ltd respectively provided the 2019‐nCoV IgG/IgM Rapid Test Cassette and COVID‐19 IgM/IgG Duo kits and the 2019‐nCoV IgG/IgM Detection Kit. Publication status: Pre‐print article Source: Pre‐print server (medRxiv) Author COI: One of the authors received immunochromatographic anti‐SARS‐CoV‐2 antibody detection kits from Nichirei Biosciences Inc. and Shionogi & Co., Ltd, none of which was related to this work.
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?	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