Determinants for detection of infection with SARS-CoV-2 Omicron variants of concern in health care workers by rapid antigen tests

IMPORTANCEThe rapid genetic evolution of SARS-CoV-2 and in particular the highly contagious Omicron variant of concern (VoC) may pose problems for rapid and accurate diagnosis of infection. OBJECTIVEDetermine the diagnostic accuracy and robustness of a second generation rapid antigen tests compared to gold-standard, PCR-based diagnostics, for detection of infection with different SARS-CoV-2 Omicron VoC sub lineages in health care workers. DESIGN, SETTING, AND PARTICIPANTSThe study included 428 health care workers from the University Hospital Munich Rechts der Isar of the Technical University of Munich who either reported recent onset of COVID-19 associated symptoms or completed routine diagnostic testing between 24th of May and 22nd of September 2022. All participants gave written informed consent to participate in this study and completed a questionnaire on infection-associated symptoms, prior SARS-CoV-2 infections and vaccination status. INTERVENTIONSDuring the first visit, two nasal swabs and one oropharyngeal swab were taken to perform two rapid antigen tests and a SARS-CoV-2 PCR-assay, respectively. A second set of nasal swabs was taken by the participants themselves two days later to repeat the two rapid antigen tests. MAIN OUTCOMES AND MEASURESThe accuracy for detection of infection with different SARS-CoV-2 Omicron VoCs with two rapid antigen tests (Test I and Test II) was determined and compared to quantitative SARS-CoV-2 RNA levels detected by PCR. RESULTSIn a side-by-side comparison, we found that Test I detected viral nucleocapsids from Omicron VoC (BA.5.2.3) at higher dilutions compared to Test II. In the 428 health care workers, Test I and Test II detected PCR-confirmed SARS-CoV-2 infection with different Omicron VoCs (BA.2, BA.4, BA.5) with a sensitivity of 89.4% (95% CI 81.9% - 94.6%) and 83.7% (95% CI 75.12% - 90.18%), respectively. Increased sensitivity of Test I was also reflected by earlier detection of SARS-CoV-2 infection. The lower test sensitivity of Test II could be compensated for by a repeated test performed two days later. CONCLUSIONS AND RELEVANCEOur study demonstrates that rapid antigen tests are suited to detect infection with the SARS-CoV-2 Omicron VoC and reveal an advantage of a lower detection limit for earlier detection of infection in health care workers.