Diagnostic accuracy of a SARS-CoV-2 rapid antigen test in real-life clinical settings.

BACKGROUND: Laboratory tests are a mainstay in managing the COVID-19 pandemic, and high hopes are placed on rapid antigen tests. However, the accuracy of rapid antigen tests in real-life clinical settings is unclear because adequately designed diagnostic accuracy studies are essentially lacking. OBJECTIVES: We aimed to assess the diagnostic accuracy of a rapid antigen test to diagnose SARS-CoV-2 infection in a primary/ secondary care testing facility. METHODS: Consecutive individuals presented at a COVID-19 testing facility affiliated to a Swiss University Hospital were recruited (n=1'465%). Nasopharyngeal swabs were obtained, and the Roche/ SD Biosensor rapid antigen test was conducted in-parallel with two real-time PCR (reference standard). RESULTS: Among 1'465 patients recruited, RT-PCR was positive in 141 individuals, corresponding to a prevalence of prevalence 9.6%. The Roche/ SD Biosensor rapid antigen test was positive in 94 patients (6.4%), and negative in 1'368 individuals (93.4%). The overall sensitivity of the rapid antigen test was 65.3% (95% confidence interval, CI, 56.8, 73.1), the specificity was 99.9% (95%CI 99.5, 100.0). In asymptomatic individuals, the sensitivity was 44.0% (95%CI 24.4, 65.1). CONCLUSIONS: The diagnostic accuracy of the SARS-CoV-2 Roche/SD Biosensor rapid antigen test to diagnose a SARS-CoV-2 infection in a primary/ secondary care testing facility was considerably lower compared to manufacturers' data. Widespread application in this setting might lead to a considerable number of individuals falsely classified as SARS-CoV-2 negative.