Accuracy and cost description of rapid antigen test compared with reverse transcriptase-polymerase chain reaction for SARS-CoV-2 detection.

Jakobsen, Kathrine Kronberg; Jensen, Jakob Schmidt; Todsen, Tobias; Tolsaard, Martin Grønnebæk; Kirkby, Nikolai; Lippert, Freddy; Vangsted, Anne-Marie; Martel, Cyril Jean-Marie; Klokker, Mads; von Buchwald, Christian

INTRODUCTION Fast and accurate detection of SARS-CoV-2 is essential in limiting the COVID-19 pandemic. Rapid antigen (AG) tests provide results within minutes; however, their accuracy has been questioned. The study aims to determine the accuracy and cost of the STANDARD Q COVID-19 AG test compared with RT-PCR. METHODS Individuals 18 years or older with an appointment for a RT-PCR test on 26-31 December 2020 at a public test centre in Copenhagen, Denmark were invited to participate. An oropharyngeal swab was collected for RT-PCR analysis, followed by a nasopharyngeal swab examined by the AG test (SD Biosensor). The diagnostic accuracy of the AG test was calculated with RT-PCR as reference. Costs were evaluated for both tests. RESULTS A total of 4,811 paired conclusive test results were collected (median age: 45 years, female: 53%). The RT-PCR test revealed 221 (4.6%) positive tests. The overall sensitivity and specificity of the AG test were 69.7% and 99.5%, respectively. Viral cycle threshold values were significantly higher in individuals with false negative AG tests than in individuals who were true positives. The RT-PCR test and AG test costs were 67.0 DKK (10.8 USD) and 35.0 DKK (5.7 USD), respectively, per positive case detected at 100,000 daily tests. CONCLUSIONS The AG test enables mass testing and provides immediate results, which is important in SARS-CoV-2 screening. The AG test is a good and relevant supplement to RT-PCR testing in public SARS-CoV-2 screenings. FUNDING This project received no external funding. Copenhagen Medical A/S delivering the rapid AG tests and provided test personnel but were not otherwise involved. TRIAL REGISTRATION Clinicaltrials.org: NCT04716088.