Diagnostic Accuracy of 2 cm Versus 4 cm Insertion Depth for Nasal Swabs for SARS-CoV-2 (COVID-19) Rapid Antigen Testing-A Randomized Controlled Trial

This study aims to compare the diagnostic accuracy of rapid antigen detection tests (RDTs) for SARS-CoV-2 using nasal swab insertion depths of 2 cm versus 4 cm. The study is an investigator-initiated, randomized clinical trial conducted at a public COVID-19 test center in Copenhagen, Denmark. Following enrollment, participants complete a questionnaire regarding symptoms and vaccination status. Participants are randomized in a 1:1 ratio to one of two sampling sequences: either a 2 cm swab in the left nostril and a 4 cm swab in the right nostril, or vice versa. All participants undergo a healthcare worker-collected throat swab for RT-PCR analysis, which serves as the reference standard for SARS-CoV-2 infection.