RSV Vaccines Modestly Reduced Hospitalizations Among Older Adults in Local Study

A study modeling the impact of recent respiratory syncytial virus (RSV) immunization strategies in King County, Washington, found that vaccinations modestly reduced RSV-related hospitalizations among older adults during the 2023-2024 season and could significantly boost protection with broader uptake in future seasons.

Using local public health surveillance data and a transmission model, researchers estimated that 125 hospitalizations were averted countywide during the latest RSV season. Adults aged 75 years and older experienced a meaningful 14.8% reduction in RSV hospitalizations compared to baseline projections. Adults aged 60 to 74 years saw smaller gains, partly due to lower vaccine uptake.

By the end of the 2023-2024 season, just 21.2% of adults aged 60 to 74 years and 32.7% of those 75 and older were immunized. The researchers project that with more aggressive vaccine coverage—reaching 50% in older adults—hospitalizations in those aged 75 and older could be cut by nearly 30% in the 2024-2025 season.

However, the study also highlights the potential limitations of adult protection over time. If RSV vaccine effectiveness in adults aged 75 and older declines by 50% in the second year, the projected benefit falls to 22.2%.

The findings underscore the need for early, widespread vaccination efforts and the importance of ongoing surveillance. As RSV vaccines for older adults become more widely adopted, the study’s use of real-world data offers valuable insight for tailoring immunization strategies and planning for potential surges during future RSV seasons.

Reference

Hansen CL, Lee L, Bents SJ, et al. Scenario projections of respiratory syncytial virus hospitalizations averted due to new immunizations. JAMA Netw Open. 2025;8(6):e2514622. doi:10.1001/jamanetworkopen.2025.14622