Yates 2021.

Study characteristics
Patient Sampling	Study design: patients with suspected COVID‐19, all symptomatic
Patient characteristics and setting	Age group: adults, perhaps also children Setting: outpatient
Index tests	Index test(s): chest X‐rays Definition for positive diagnosis on X‐rays: unclear Level of training of readers: unclear Prevalence: 0.25
Target condition and reference standard(s)	Reference standard: RT‐PCR twice, in all with initial negative results
Flow and timing
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?	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?			Low concern
DOMAIN 2: Index Test (Chest CT)
DOMAIN 2: Index Test (Chest X‐ray)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 2: Index Test (Ultrasound of the lungs)
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?	Yes
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

Abbreviations: ACR: American College of Radiology; AI: artificial intelligence; BSTI: British Society of Thoracic Imaging; CO‐RADS: COVID‐19 Reporting and Data System; CT: computed tomography; GGO: ground‐glass opacity; IV: intravenous; POCUS: point‐of‐care ultrasound; RSNA: Radiological Society of North America; RT‐PCR: reverse transcriptase polymerase chain reaction; STR: Society of Thoracic Radiology; US: ultrasound