Analytical performance of rapid antigen tests for the detection of SARS-CoV-2 during widespread circulation of the Omicron variant

Introduction Antigen testing is essential in the clinical management of COVID-19. However, most evaluations of antigen tests have been performed before the emergence of the Omicron variant. Thus, an assessment of the diagnostic performance of antigen tests for the detection of SARS-CoV-2 during the circulation of Omicron variant is required. Methods This prospective observational study evaluated QuickNavi-COVID19 Ag, a rapid antigen detection test between December 2021 and February 2022 in Japan, using real-time reverse transcription (RT)-PCR as a reference. Two nasopharyngeal samples were simultaneously collected for antigen testing and for RT-PCR. Variant analysis of the SARS-CoV-2 genomic sequencing was also performed. Results In total, nasopharyngeal samples were collected from 1,073 participants (417 positive; 919 symptomatic; 154 asymptomatic) for analysis. Compared with those of RT-PCR, the sensitivity, specificity, positive predictive value, and negative predictive value were 94.2% (95% CI: 91.6%–96.3%), 99.5% (95% CI: 98.7%–99.9%), 99.2% (95% CI: 97.8%–99.8%), and 96.5% (95% CI: 94.8%–97.7%), respectively. The sensitivity among symptomatic individuals was 94.3% (95% CI: 91.5%–96.4%). Overall, 85.9% of sequences were classified as Omicron sublineage BA.1, 12.4% were Omicron sublineage BA.2, and 1.6% were Delta B.1.617.2. (Delta variant). Most of the samples (87.1%) had Ct values <25. Conclusions The QuickNavi-COVID19 Ag test showed high diagnostic performance for the detection of the SARS-CoV-2 Omicron sublineages BA.1 and BA.2 from nasopharyngeal samples. ### Competing Interest Statement Denka Co., Ltd. provided funds for research expenses and the QuickNavi-Flu+COVID19 Ag and QuickNavi-COVID19 Ag tests without charge. Hiromichi Suzuki received a lecture fee from Otsuka Pharmaceutical Co., Ltd. Daisuke Kato, Miwa Kuwahara and Shino Muramatsu work for Denka Co., Ltd., the developer of the QuickNavi-Flu+COVID19 Ag and QuickNavi-COVID19 Ag tests. ### Funding Statement Denka Co., Ltd. provided funds for research expenses and the QuickNavi-Flu+COVID19 Ag and QuickNavi-COVID19 Ag tests without charge. Hiromichi Suzuki received a lecture fee from Otsuka Pharmaceutical Co., Ltd. Daisuke Kato, Miwa Kuwahara and Shino Muramatsu work for Denka Co., Ltd., the developer of the QuickNavi-Flu+COVID19 Ag and QuickNavi-COVID19 Ag tests. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The ethics board of the University of Tsukuba Hospital approved the study (approval number: R03-042), including the method of obtaining informed consent. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors