Exploring RSV transmission patterns in different age groups in the United States

Respiratory syncytial virus (RSV) infections are a significant public health concern for pediatric populations and older adults, with seasonal winter outbreaks in the United States (US). Little is known about the timing of RSV epidemics across age groups and the relative contribution of within-group and between-group transmission of RSV in each age group. In this study, we analyzed RSV timing and transmission across age groups in 12 states from 2018 to 2024. We found that children under 5 had the earliest epidemic peaks; the elderly had the latest. An age-structured time series model showed >50% of hospitalizations in several age groups were due to between-group transmission, except in the elderly (above 65 years), where within-group spread dominated. Our findings indicate that distinct age groups play unique roles in propagating RSV epidemics in the US, with age-specific transmission patterns that can guide more effective RSV vaccination policies.