Abstract
BACKGROUND: The frequency and clinical profile of respiratory syncytial virus (RSV)-acute respiratory disease (ARD) in older adults in Japan has not been well-characterized. METHODS: This was a multicenter prospective observational cohort study to evaluate the occurrence rate of ARD in 1000 older adult participants (≥65 years) for 52 weeks during the 2019 to 2020 season. A multiplex polymerase chain reaction panel was used for pathogen detection in nasopharyngeal swab from participants diagnosed with ARD. Symptoms and impact of ARD was assessed using the Respiratory Infection Intensity and Impact Questionnaire (RiiQ™). The study was registered at UMIN (https://www.umin.ac.jp/ctr/): UMIN000037891. RESULTS: RSV-ARD was detected in 24/1000 (2.4%) participants and RSV-lower respiratory tract disease in 8/1000 (0.8%) participants. The median duration of RSV-ARD was 18 days. All 24 participants had utilized the medical services of outpatient visits and only 1 (4.2%) participant was hospitalized for RSV-ARD. The most common viruses other than RSV that caused ARD (detected in >10 participants) were human rhinovirus/enterovirus, parainfluenza 3, coronavirus OC43, human metapneumovirus, and influenza A/H1. The most frequent symptoms of RSV-ARD were cough, sore throat, nasal congestion, and expectoration. CONCLUSIONS: RSV was reported as a major pathogen for respiratory infections in older adults in Japan.