Abstract
BACKGROUND: Respiratory syncytial virus (RSV) is a pathogenic respiratory virus that is considered to affect not only children but also adults, especially elderly persons aged ≥65 years. However, in Japan, the annual epidemic situation and severity of RSV infections in these adults have not yet been clarified, especially during the COVID-19 pandemic. METHODS: The epidemic of RSV, especially the number of adults with RSV infection during the COVID-19 period, was retrospectively analyzed. In addition, the clinical features of patients aged ≥65 years (older group) and those aged ≤64 years (younger group) were compared. RESULTS: A total of 58 patients were found to have RSV infections from April to August 2021. Ten were adults, and five each were detected in June and July, respectively. Of the 10 adult patients, three were in the older group and were more often infected by their grandchildren, and seven were in the younger group. All older patients had underlying diseases, including diabetes mellitus. In addition, the older group showed more severe inflammation, such as increased white blood cell counts and C-reactive protein levels, and received antibiotic therapy, whereas no antibiotics were used for the younger group. Two of the three older patients were admitted to our hospital, but survived. CONCLUSION: These data suggest that RSV infection in adult patients was related to the increase in pediatric RSV patients and that the infection season had shifted to summer, similar to other countries. Among the adult RSV patients, those aged ≥65 years were more often infected by their grandchildren and received antibiotics because of their more severe inflammatory status than patients aged ≤64 years during the COVID-19 pandemic in Japan.