Yan 2020a.

Study characteristics
Patient Sampling	Purpose: to evaluate association of patient‐reported symptoms with a focus on sense of smell and taste and SARS‐CoV‐2 infection Design: internet survey of patients after presentation to a single‐centre Recruitment: email invitation with 1 phone call follow‐up to everyone who was tested for COVID‐19 between 3 March 2020 and 29 March 2020 Sample size: n = 262 (cases: 59) Inclusion criteria: adult patients who presented to the institution and got tested for COVID‐19 analysis on responders to email survey (responses: cases 59/102, controls 203/1378) Exclusion criteria:
Patient characteristics and setting	Facility cases: SARS‐CoV‐2‐positive Facility controls: SARS‐CoV‐2‐negative Country: USA, San Diego Dates: 3 March 2020‐29 March 2020 Symptoms and severity: larger representation of ambulatory patients (higher response rate to survey) severity ‐ hospital admission: cases 4/59, controls 14/203 Demographics: adults only, M/F: cases 29/29, controls 69/132 Exposure history: not specified
Index tests	Fatigue Loss of taste Fever Loss of sense of smell Cough Headache Myalgia Dyspnoea Diarrhoea Nasal obstruction Sore throat Rhinorrhoea Nausea
Target condition and reference standard(s)	TC: SARS‐CoV‐2 infection RS: PCR for SARS‐CoV‐2 (sample not specified)
Flow and timing	PCR taken at presentation, not specified when the questionnaire was sent. Patients had to list their symptoms at presentation.
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?	Yes
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	Unclear
Could the selection of patients have introduced bias?		Unclear 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?	No
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?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	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?			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?		Unclear risk