Scohy 2020.

Study characteristics
Patient Sampling	Single group study including NP swabs submitted to laboratory at a large tertiary hospital (n=148) Recruitment: Random sample Prospective or retrospective: Not stated
Patient characteristics and setting	Setting: Unclear; presume microbiology laboratory takes samples from number of sources Location: Cliniques universitaires Saint‐Luc Hospital, Brussels Country: Belgium Dates: Apr 6 to Apr 21, 2020 Symptoms and severity: 86 (58%) symptomatic, 45 (30%) asymptomatic, 17 (11%) symptom status not reported; Cases only: viral load <25 Ct 10 (9%), >=25 Ct 96 (91%) Demographics: median age 57.5 (0, 94y); 64 (43%) male Exposure history: Not reported
Index tests	Test name: COVID‐19 Ag Respi‐Strip (product code not reported) Manufacturer: Coris Bioconcept Antibody: NP Antigen target: monoclonal antibody Test method: CGIA Samples used: NP Transport media: Not stated Sample storage: "If the rapid antigen test was not performed immediately, samples were stored at 4 °C until the test" Test operator: Not stated Definition of test positivity: Visual appearance of T line; also states that "Two versions of the test were evaluated. On the second version, conjugate was coupled on a different way and the control line was optimized." Blinding reported: Unclear Timing of samples: Not reported
Target condition and reference standard(s)	Reference standard: RT‐PCR: genesig® Real‐Time PCR assay (Primerdesign Ltd, Chandler’s Ford, UK); <40 Ct Definition of non‐COVID cases: Single PCR negative Genetic target(s): RdRp Samples used: NP; same as for index 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: Same sample All patients received same reference standard: Yes Missing data: None reported, no participant flow diagram reported Uninterpretable results: None reported Indeterminate results (index test): None reported Indeterminate results (reference standard): None reported Unit of analysis: Patients
Comparative
Notes	Funding: No funding statement reported; COVID‐19 Ag Respi‐Strip tests provided by Coris BioConcept. Publication status: Published Source: J Clin Virol Author COI: The authors declare no conflicts of interest.
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 (Antigen 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 2: Index Test (Rapid molecular tests)
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?	Yes
Reference standard does not incorporate result of index test?	Yes
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?	Yes
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