Fafi‐Kremer 2020.

Study characteristics
Patient Sampling	Purpose: Assessment of antibody kinetics in individuals who had recovered from mild COVID‐19 Design: Single‐group study estimating sensitivity only: [1] hospital staff with mild PCR‐confirmed COVID‐19 (n = 160); included doctors, nurses, physiotherapists, dentists, medical students, orderlies, hospital assistants, and hospital administrative staff Recruitment: Likely consecutive; described including 'all' eligible staff within specific dates Prospective or retrospective: Not explicitly stated, but likely prospective Sample size: 160 (160) Further detail: Inclusion was conditional of informed consent. Excluded 2 patients who were hospitalised
Patient characteristics and setting	Setting: Tertiary hospital staff; cluster infected following outbreak Suggested code as 'outpatient' or 'community' as they were not inpatient; or even as contacts or outbreak investigation (need new covariate) Location: Strasbourg University Hospitals Country: France Dates: 6‐8 April 2020 Symptoms and severity: Severity: all described as mild disease; symptoms classified as minor 5 (3%) or major 155/160 (97%) (cough, fever, dyspnoea, anosmia and ageusia) Demographics: Age, median (IQR): 32 (26‐44) Sex: 50/160 (31.2%) male Exposure history: Contact with COVID‐19 patients: yes 74/160 (46.3%), no 80/160 (50%), missing 6/160 (3.7%). Level of exposure to COVID‐19 patients: none 10/75 (13.5%), some 27/75 (36.5%), high 37/75 (50%). Non‐Covid group 1: NA Source: NA Characteristics: NA
Index tests	Test name: COVID‐19 BSS IgG/IgM [Data for a second in‐house test (flow cytometry based) were reported but not included in the review] Manufacturer: Biosynex Antibody: IgG and IgM Antigen target: S‐protein Evaluation setting: POC test, evaluated in lab setting Test method: Lateral flow assay Timing of samples: Time between symptom onset and sample collection: median 24 days (IQR 21 to 28) 13‐20 days: 29/160 (18%) 21‐27 days: 83/160 (52%) 28‐41 days: 48/160 (30%) Samples used: Serum Test operator: Not stated; presume lab scientist Definition of test positivity: Not stated Blinding reported: Not stated Threshold predefined: Yes (visual result)
Target condition and reference standard(s)	Reference standard: PCR test (not further specified) Samples used: Not stated Timing of reference standard: Time from symptom onset to PCR‐positive in days, median (IQR): 2 (1‐4) Blinded to index test: Yes (done earlier) Incorporated index test: No Definition of non‐COVID cases: NA
Flow and timing	Time interval between index and reference tests: Approx 3 weeks (based on median times reported) All patients received same reference standard: Yes Missing data: None reported Uninterpretable results: None reported Indeterminate results: None reported Unit of analysis: Patients
Comparative
Notes	Funding: No specific funds for this work, but the labs where the study was done receive funding from multiple sources (Institut Pasteur, ANRS, Sidaction, Vaccine Research Institute, Labex IBEID, TIMTAMDEN, CHIKViro‐Immuno, Gilead HIV cure programme, French Ministry of Higher Education‐Research‐Innovation, Strasbourg University Hospitals). Publication status: Published article Source: Academic journal Author COI: One author is founder and CSO of TheraVectys; four other authors hold a provisional patent on the S‐flow assay; one author reported grants and/or personal fees from Mylan, ViiV Healthcare, Gilead, Abbvie.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Yes
Did the study avoid inappropriate inclusions?	Yes
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?	Unclear
Were all patients included in the analysis?	Yes
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		Unclear risk