Yongchen 2020.

Study characteristics
Patient Sampling	Purpose: one‐group study recruiting patients estimating sensitivity Design: [1] 11 non‐severe COVID‐19 patients [2] 5 severe COVID‐19 patients [3] 5 asymptomatic carriers Recruitment: retrospective Sample size (virus/COVID cases): 21 (21) Inclusion and exclusion criteria: no more details available
Patient characteristics and setting	Setting: Hospital Location: 2 medical centres ‐ Second Hospital of Nanjing and the Affiliated Hospital of Xuzhou Medical University in Jiangsu Province Country: China Dates: 25 January‐18 March 2020 Symptoms and severity: 5 severe, 11 non‐severe and 5 asymptomatic cases. Asymptomatic carriers were defined as individuals who were positive for COVID‐19 nucleic acid but without any symptoms during screening of close contacts. Sex: 13/21 (62%) male; age: median (range) = 37 (10‐73) Exposure history: NR
Index tests	Test name: no commercial name stated Manufacturer: Innovita Co., Ltd, China Ab targets: IgG and IgM Antigens used: SARS‐CoV‐2 S‐protein and N‐protein Test method: GICA Timing of samples: IPD presented in Fig 1; 1 sample included per patient per time slot Samples used: serum Test operators: NR Definition of test positivity: NR Blinded to reference standard: NR and no assumptions made based on timing of the test Threshold predefined: NR
Target condition and reference standard(s)	Reference standard for cases: RT‐PCR ‐ confirmed after 2 sequential positive respiratory tract sample results Samples used: throat swabs Timing of reference standard: throat swab samples collected every 1‐2 days Blinded to index test: yes (serum samples for serological evaluation were stored for later evaluation) Incorporated index test: no Reference standard for non‐cases: NA
Flow and timing	Time interval between index and reference tests: NR Results presented by time period: yes All participants received the same reference standard: yes Missing data: NR Uninterpretable results: NR Indeterminate results: NR Unit of analysis: participant
Comparative
Notes	Funding: supported by the National Natural Science Foundation of China, Jiangsu Provincial Medical Talent, Six talent peaks project of Jiangsu Province, Advanced health talent of six‐one project of Jiangsu Province, Nanjing Medical Science and Technique Development Foundation Publication status: published paper Source: Emerging Microbes & Infections Study author COI: none was declared
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?	Unclear
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?	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