Diagnostic accuracy of rapid antigen tests for detection of Delta and Omicron variants of severe acute respiratory syndrome coronavirus 2: Direct evidence from prospective clinical settings

Despite widespread application during the coronavirus disease-19 pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection using patient-performed rapid antigen tests (RATs) is limited, especially regarding the Delta and Omicron variants. Therefore, in this study, we evaluated the performance of RATs in identifying Delta and Omicron infections in self-test settings. In this multicenter clinical performance study conducted in Korea between November 2021 and February 2022, we included participants without prior diagnostic device experience. Using 2 RAT types, we compared the results with real-time reverse transcriptase-polymerase chain reaction testing, focusing on clinical sensitivity and specificity. Reverse transcriptase-polymerase chain reaction helped confirm 77 SARS-CoV-2 infections among 280 participants. RATs exhibited high positive agreement for Omicron detection but lower rates for Delta, especially among partially vaccinated individuals. This study provides direct evidence that RATs, originally developed for ancestral strains of SARS-CoV-2, effectively detect major variants such as Delta and Omicron in real patient/clinical settings. By confirming variant presence through sequencing, our research offers significant and novel insights into the performance of RATs, particularly in the context of breakthrough infections postvaccination, with precise data on vaccination status and timing obtained from government records.