Sensitivity of Rapid Antigen Tests Against SARS-CoV-2 Omicron and Delta Variants

• DOI: 10.1101/2023.02.09.23285583
• Publication Date: 2023-02-10T18:15:19Z
• Authors: Anuradha Rao; Adrianna Westbrook; Leda Bassit; Richard Parsons; Eric Fitts; Morgan Greenleaf; Kaleb McLendon; Julie A. Sullivan; William O’Sick; Tyler Baugh; Heather B. Bowers; Filipp Frank; Ethan Wang; Mimi Le; Jennifer Frediani; Pavitra Roychoudhury; Alexander L. Gren...; Robert Jerris; Nira R. Pollock; Eric A. Ortlund; John D. Roback; Wilbur A. Lam; Anne Piantadosi
• Keywords: 0301 basic medicine; 03 medical and health sciences; SARS-CoV-2; Virology; Humans; COVID-19; RNA; Pandemics; Article; 3. Good health

AbstractRapid Antigen Tests (RAT) have become an invaluable tool for combating the COVID-19 pandemic. However, concerns have been raised regarding the ability of existing RATs to effectively detect emerging SARS-CoV-2 variants. We compared the performance of eight commercially available, emergency use authorized RATs against the Delta and Omicron SARS-CoV-2 variants using individual patient and serially diluted pooled clinical samples. The RATs exhibited lower sensitivity for Omicron samples when using PCR Cycle threshold (CT) value (a proxy for RNA concentration) as the comparator. Interestingly, however, they exhibited similar sensitivity for Omicron and Delta samples when using quantitative antigen concentration as the comparator. We further found that the Omicron samples had lower ratios of antigen to RNA, which offers a potential explanation for the apparent lower sensitivity of RATs for that variant when using CTvalue as a reference. Our findings underscore the complexity in assessing RAT performance against emerging variants and highlight the need for ongoing evaluation in the face of changing population immunity and virus evolution.