Hsih 2020.

Study characteristics
Patient Sampling	Patients admitted to China Medical University Hospital meeting the screening criteria of COVID‐19 reported by Taiwan CDC (travel history to China and presented fever or any respiratory symptoms within 14 days). All eligible patients were included.
Patient characteristics and setting	Setting: hospital, emergency room Country: Taiwan Symptoms and severity: most common symptoms were fever, nonproductive cough, rhinorrhoea, sore throat, productive cough and dyspnea Demographics: mean age 34 (range 3‐68), female 60% Exposure history: travel to China, contact with people travelling to China, or contact with COVID‐19 patients Time since onset of symptoms: not reported
Index tests	Index tests (threshold): WBC count increased (11.2 x 109/L) WBC count decreased (3.6 x 109/L) Lymphocyte count decreased (1.0 x 109/L) CRP increased (10 mg/L) For all tests Sample: blood product, whole blood (not reported, but otherwise WBC impossible) Test interpreter: not reported Timing of testing: not reported
Target condition and reference standard(s)	RT‐PCR (conducted multiple times in each participant; at least upon admission and 24h after admission, and for some participants even every few days). Target condition was SARS‐CoV‐2 infection. Sample: naso‐oropharyngeal specimen, sputum Threshold: not reported
Flow and timing	Time interval between index test and reference standard: not clearly reported Verification: all participants received the same reference standard Missing data: no missing data or uninterpretable results
Comparative
Notes	Funding: this study was supported by a grant, CMUH DMR‐108‐189, from China Medical University Hospital, Taichung, Taiwan.
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?	Yes
Did the study avoid inappropriate exclusions?	Yes
Could the selection of patients have introduced bias?		Low risk
Are there concerns that the included patients and setting do not match the review question?			Unclear
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?	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?			Unclear
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	No
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?		High 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
Could the patient flow have introduced bias?		Unclear risk