Qiu 2020.

Study characteristics
Patient Sampling	Purpose: Detection of acute or convalescent‐phase Covid infection Design: Two‐group study to estimate sensitivity and specificity: [1] Confirmed Covid cases n = 475 [2] Non‐Covid controls, concurrent non‐COVID patients n = 389 Recruitment: [1] and [2] Individuals enrolled from four medical institutions in Hubei Province between January 20 2020 and March 12 2020 Prospective or retrospective: Retrospective Sample size: 864 (475) Further detail: Included adults >= 18 years age Excluded pregnant women
Patient characteristics and setting	Setting: Hospital inpatients. Location: Four medical institutions, Hubei province: Zhongnan Hospital of Wuhan University, Wuhan Third Hospital‐Tongren Hospital of Wuhan University, Huang Gang Central Hospital, Hebi City Centre for Disease Control and Prevention Country: China Dates: Between January 20 2020 and March 12 2020 Symptoms and severity: Hospital inpatients, symptoms recorded but data not shown Demographics: Of 409 cases used for Ab testing: 217 males, 192 females, median age 60 years (IQR, 49‐69) Exposure history: Not stated Non‐Covid group 1: Non‐Covid controls Source: Hospital inpatients Four medical institutions between January 20 2020 and March 12 2020, Hubei province: Zhongnan Hospital of Wuhan University, Wuhan Third Hospital‐Tongren Hospital of Wuhan University, Huang Gang Central Hospital, Hebi City Centre for Disease Control and Prevention Characteristics: 224 males, 165 females; median age 45 years (IQR, 29‐61)
Index tests	Test name: SARS‐CoV‐2 IgG and IgM CLIA Microparticle detection kit Manufacturer: Autobio Diagnostics Co., Ltd. (Henan, China) Antibody: IgG or IgM Antigen target: S‐protein Evaluation setting: Laboratory Test method: CLIA Timing of samples: 1 to 87 days pso 1‐10 days pso: 66/409 11‐20 days pso: 70/409 21+ days pso: 273/409 Samples used: Serum Test operator: Laboratory staff Definition of test positivity: S/CO >= 1 Blinding reported: Unclear Threshold predefined: Yes
Target condition and reference standard(s)	Reference standard: RT‐qPCR, the target genes included the open reading frame 1ab (ORF1ab) gene, and the nucleocapsid protein (N) gene of SARS‐CoV2, analysed according to manufacturer’s protocol. Samples used: Throat swabs Timing of reference standard: Not stated Blinded to index test: Yes Incorporated index test: No Definition of non‐COVID cases: RT‐qPCR, the target genes included the open reading frame 1ab (ORF1ab) gene, and the nucleocapsid protein (N) gene of SARS‐CoV2, analysed according to manufacturer’s protocol. Samples used: throat swabs Timing of reference standard: Not stated Blinded to index test: Yes Incorporated index test: No
Flow and timing	Time interval between index and reference tests: Not clear, time between symptom onset and collection of serum samples for index test ranged from 1 to 87 days. All patients received same reference standard: Yes Missing data: 475 Covid patients recruited, results only available for 409 cases Uninterpretable results: Not stated Indeterminate results: Not stated Unit of analysis: Patients
Comparative
Notes	Funding: Work supported by Hubei Province Health and Family Planning Scientific Research Project Publication status: Published paper Source: Emerging Microbes & Infections Author COI: No COI 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?	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?	Unclear
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?		Unclear 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?	Yes
Did all participants receive a reference standard?	No
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		High risk