Ai 2020a.

Study characteristics
Patient Sampling	Purpose: diagnosis of SARS‐CoV‐2 pneumonia Design: cross‐sectional multicentre prospective study Recruitment: hospitalised pneumonia patients Sample size: n = 53 (20 cases) Inclusion criteria: suspected SARS‐COV‐2 pneumonia patients, defined as having pneumonia after chest CT (with 1 of the 2 following criteria met: fever or respiratory symptoms, normal or decreased WBC counts/decreased Exclusion criteria: not defined
Patient characteristics and setting	Facility cases: confirmed case: a positive SARS‐COV‐2 nucleotides result either by metagenomic sequencing or RT‐PCR assay for nasopharyngeal swab specimens Facility controls: pneumonia patients confirmed not to be infected by SARS‐Cov2 (2 PCR tests, 2 days in between) Country: China Dates: 22 January 2020‐19 February 2020 Symptoms and severity: suspected SARS‐COV‐2 pneumonia (NCP): having pneumonia after chest CT with 1 of the 2 following criteria met: fever or respiratory symptoms, normal or decreased WBC counts/decreased lymphocyte counts, and a travel history or contact with patients with fever or respiratory symptoms from Hubei Province or confirmed cases within 2 weeks Demographics: median age cases 37 years, controls 39 years, gender distribution cases (M/F: 50/50), controls (M/F: 48.5/51.5) Exposure history: not specified
Index tests	Fever Dry cough Diarrhoea Fatigue Headache Vomiting Abdominal pain
Target condition and reference standard(s)	TC: COVID‐19 pneumonia RS: a positive SARS‐COV‐2 nucleotides result either by metagenomic sequencing or RT‐PCR assay for nasopharyngeal swab specimens, repeated after 2 days if negative on day 0
Flow and timing	Time interval not specified. Reference standard at day 0 and day 2, index tests from electronic medical records but stated at pneumonia onset
Comparative
Notes
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?	Yes
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	No
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)
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?	No
Could the conduct or interpretation of the index test have introduced bias?		High 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
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?			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?	Yes
Could the patient flow have introduced bias?		Low risk