Gao 2020a.

Study characteristics
Patient Sampling	Single‐group study estimating sensitivity [1] Patients with confirmed COVID‐19 (n = 38) Recruitment: unclear Sample size (virus/COVID cases): 38 (38) Inclusion and exclusion criteria: COVID‐19 confirmed by New Coronavirus Pneumonia Prevention and Control Program (5th edition) published by the National Health Commission of China
Patient characteristics and setting	Setting: hospital inpatient Location: Second People's Hospital of Fuyang Country: China Dates: 22 January 2020‐28 February 2020 Symptoms and severity: 3/38 described as in severe or critical conditions; 35/38 described as mild cases Sex: 55.3% (21/38) male Age: median age 40.5 years (IQR 31.0‐49.5 years), range 15‐75 years Exposure history: NR
Index tests	Test name: Colloidal Gold Antibodies Test Manufacturer: Innovita Biological Technology Co., Ltd Ab targets: IgM, IgG Antigens used: NR Test method: CGIA Timing of samples: days 0‐15+ Samples used: serum Test operators: NR Definition of test positivity: visible line Blinded to reference standard: NR Threshold predefined: yes
Target condition and reference standard(s)	Reference standard for cases: participants met the criteria of the New Coronavirus Pneumonia Prevention and Control Program (5th edition) published by the National Health Commission of China. Samples used: NR Timing of reference standard: NR Blinded to index test: yes Incorporated index test: no
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: yes: 0‐7 days (n = 13), 8‐14 days (n = 8) and ≥ 15 days (n = 23) after onset of symptoms All participants received the same reference standard: yes Missing data: NR Uninterpretable results: NR Indeterminate results: NR Unit of analysis: results reported for participants. 38 participants included and 76 serum samples collected in total from these 38 participants. Median number of samples collected from each participant was 8.
Comparative
Notes	Funding: The Science and Technology Bureau of Fuyang Publication status: accepted manuscript (peer reviewed) Source: Journal of Medical Virology Study author COI: none reported
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?	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?			Low concern
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?	Unclear
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
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