No detection of respiratory syncytial virus at one clinic in Japan with rapid immunochromatographic antigen tests for three viruses using the same nasopharyngeal swabs from adult patients

The disease burden of respiratory syncytial virus (RSV) infection in Japanese adults has been attracting attention. Nasopharyngeal swabs were collected from 141 patients aged 18 years and older who visited a Japanese clinic from August 2024 to July 2025 with symptoms of an acute respiratory infection. These samples were tested using rapid immunochromatographic antigen tests for SARS-CoV-2, influenza viruses A and B, and RSV. The results showed that 32 patients tested positive for SARS-CoV-2, 31 for influenza virus A, and one for influenza virus B, whereas no RSV-positive patients were detected. Compared with five previous reports using polymerase-chain reaction (PCR) testing (RSV-positive: 88 of 2974 patients), the number of RSV-positive patients was lower (chi-squared test p=0.04123), suggesting that the rapid immunochromatographic antigen test is not useful for diagnosing RSV infections in adults in Japan.