Burden and clinical characteristics of respiratory syncytial virus infection in older adults in the outpatient setting in Germany: a prospective multiseason study

Respiratory syncytial virus (RSV) is a leading cause of acute respiratory infections (ARI), yet evidence from outpatient settings, particularly among older adults, remains limited. BUCOSS was a prospective observational study conducted across three consecutive respiratory seasons (2022–2025) in patients aged ≥ 60 years with ARI, recruited from 29 primary care and office-based pulmonology practices. RSV and other respiratory pathogens were identified via multiplex polymerase chain reaction (PCR) of nasopharyngeal swabs. RSV-positive patients were followed for 28 days to assess symptom burden, complications and health-related quality of life (HRQoL). RSV had a prevalence of 5.49% (95% CI: 2.96–8.03) and an incidence of 1,030.63/100,000 (95% CI: 824.48–1,287.66). Among 3,261 patients with ARI, 192 (5.9%) tested positive for RSV. The mean age of RSV-infected individuals was 71.6 years; 90.6% had at least one comorbidity. RSV infection was associated with a significantly higher burden of lower respiratory tract symptoms — notably cough, sputum production and wheezing — compared with other viral ARI, whereas systemic symptoms such as fever and myalgia were less prominent. Within 28 days, 30% of RSV-positive patients developed complications, predominantly pulmonary. Chronic lung disease (RR1.62 (0.95; 2.77)) and the presence of lower respiratory tract symptoms at presentation (RR 1.78 (0.92; 3.45)) trended to be independently associated with increased complication risk. RSV constitutes a substantial cause of ARI in older, multimorbid outpatients, distinguished by a pronounced lower respiratory tract symptom profile and a high rate of pulmonary complications. These findings underscore the need for targeted prevention strategies and tailored clinical management in high-risk adult populations.