Burden of respiratory syncytial virus infections in older adults with acute respiratory infection in Japan: An epidemiological study among outpatients

Background

Respiratory syncytial virus (RSV) is a leading cause of acute respiratory illness, with severe outcomes in older adults. Information on the prevalence, hospitalization rate, and impact on the health-related quality of life (HRQoL) of RSV in older adults with acute respiratory infections (ARI) in outpatient settings in Japan is limited.

Methods

This multi-center epidemiological study included outpatients aged ≥60 years presenting with ARI between August 2021 and February 2023. Nasal and throat swabs were collected and tested by reverse transcription polymerase chain reaction (RT-PCR). The prevalence of RT-PCR-confirmed RSV (cRSV)-ARI, cRSV-lower respiratory tract disease (LRTD), and other respiratory viruses was calculated by season, region, age group, and RSV subtype. HRQoL was assessed via patient-reported outcomes.

Results

The study included 923 ARI episodes (cRSV-ARI: N = 24; non-cRSV-ARI: N = 899). In years 1 and 2 (August 2021–July 2022 and August 2022–February 2023), the prevalence of cRSV-ARI was 2.5% and 2.8%, respectively. There was a predominance of RSV-B and RSV-A subtypes in years 1 and 2, respectively. In years 1 and 2 combined, 37.5% of cRSV-ARI cases had lower respiratory tract infection; all cRSV-LRTD cases occurred in those aged 60–74 years. RSV-ARI cases reported throat, chest, and respiratory symptoms, leading to impaired functioning and HRQoL.

Conclusions

During the observed study period, RSV was circulating among older adults in Japan. RSV was a leading cause of ARI and LRTD. More data are needed to fully clarify the burden of RSV among older adults in Japan.