Clinical accuracy of SARS-CoV-2 rapid antigen testing in screening children and adolescents in comparison to RT-qPCR, November 2020 to September 2022

Background Rapid antigen detection tests (RDT) are an easily accessible, feasible, inexpensive, and point-of-care method in SARS-CoV-2 diagnostics – established in adults as well as in children and adolescents. Despite this, large-scale data of clinical performance in the paediatric population especially regarding the influence of SARS-CoV-2 virus variants of concern (VOC) and COVID-19 vaccination on test accuracy is rare. Methods This single-centre prospective diagnostic study evaluates three RDT (NADAL®, Panbio™, MEDsan®) in comparison to quantitative reverse transcription polymerase chain reaction (RT-qPCR). 9,760 oropharyngeal screening samples regarding SARS-CoV-2 VOC and COVID-19 vaccination in paediatric hospitalised patients aged younger than 18 years were enrolled. Findings RDT sensitivity was 44·7% (157/351, 95% CI 39·6%–50·0%) compared to the reference standard RT-qPCR, specificity 99·8% (9,392/9,409, 95% CI 99·7%–99·9%). Most SARS-CoV-2 infections considered were caused by Omicron VOC. Diagnostic accuracy of RDT depended on specimen containing viral load with a decreasing RDT sensitivity by descending viral load, corresponding with a significantly impaired sensitivity in asymptomatic children. A sensitivity of 71·0% was obtained for a viral load higher than 10 6 SARS-CoV-2 RNA copies per ml suggested as infectivity threshold. No significant differences in RDT sensitivity could be observed regarding gender, symptoms, COVID-19 vaccination status, and VOC. Interpretation In a paediatric population, RDT have proven to reliably detect potentially highly infectious patients with a viral load of at least 10 6 SARS-CoV-2 RNA copies per ml. Due to the low sensitivity in asymptomatic individuals, the usefulness of RDT seems limited in large-scale SARS-CoV-2 screening programs. Funding Federal Ministry for Education and Science (BMBF), Free State of Bavaria