Background: Rapid antigen tests (RATs) are widely used in clinical settings, aiding in the prevention of infectious diseases. However, there is a lack of research on the performance of RATs that can simultaneously diagnose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Influenza A/B viruses. In this study, we aimed to evaluate the performance of a newly developed RAT that can detect all three pathogens at once, to assess its potential for clinical application.
Methods: Clinical performance testing was conducted using 436 nasopharyngeal swab samples collected from patients with suspected respiratory infections. The newly developed RAT was compared with realtime reverse transcription-polymerase chain reaction (rRT-PCR) results to evaluate clinical sensitivity and specificity. Additionally, concordance with two previously approved products was assessed.
Results: For patients who tested positive with rRT-PCR, the detection sensitivity of the newly developed INCLIX TRF COVID-19 & Flu A/B Ag test was 90.91% for SARS-CoV-2, 97.75% for Influenza A, and 93.00% for Influenza B, with a specificity of 100% for all three pathogens. In the concordance assessment with the existing RATs, the agreement was 99.76% (κ=0.9922) for SARS-CoV-2, 99.76% (κ=0.9927) for Influenza A, and 99.76% (κ=0.9930) for Influenza B. Compared to the existing RATs, all showed a concordance with κ >0.8.
Conclusions: The INCLIX TRF COVID-19 & Flu A/B Ag test efficiently detected antigens of SARS-CoV-2 and Influenza A/B viruses simultaneously within a short testing time of 15 minutes. Therefore, this test method, with its high sensitivity and specificity, will be highly useful for diagnosing viral infections in clinical settings.

Keywords: SARS-CoV-2, Influenza A, Influenza B, Rapid antigen test