Respiratory syncytial virus vaccination reduced the risk of hospitalization by 75% in adults aged 60 years and older, according to a recent study.
The study, published in JAMA, evaluated the effectiveness of respiratory syncytial virus (RSV) vaccination in preventing RSV-associated hospitalizations among older U.S. adults during the 2023–2024 season. This investigation followed the June 2023 Centers for Disease Control and Prevention (CDC) recommendation for RSV vaccination in older adults based on prelicensure trials that demonstrated the vaccine's high efficacy against RSV lower respiratory tract disease but lacked data on hospitalization outcomes.
This test-negative, case-control study included just under 3,000 adults who were hospitalized for acute respiratory illness across 19 states between October 2023 and March 2024. RSV vaccination status—confirmed through electronic medical records, immunization registries, and self-reporting—was compared between 367 RSV-positive cases and 2,611 RSV-negative controls.
Among the 2,978 adults, 12.3% (367) tested positive for RSV, while 87.7% (2,611) tested negative, serving as controls; 2.5% of RSV-positive patients had been vaccinated, compared to 9.8% of RSV-negative controls. Out of 288 RSV-positive patients with identified subtypes, 72.9% (210) were found to have the RSV B strain. The median age of vaccinated patients was 75 years, while unvaccinated patients had a median age of 72 years (P < .001). Additionally, 31.7% of vaccinated patients were immunocompromised compared to 23.4% of unvaccinated patients (P < .01). The median Social Vulnerability Index for vaccinated patients was 0.37, compared to 0.58 for unvaccinated patients (P < .001).
Researchers found that RSV vaccination was associated with a 75% reduction in the risk of RSV-associated hospitalization (95% confidence interval [CI] = 50%–87%). This effectiveness was consistent across age groups, with a 75% reduction in adults aged 60 to 74 years and a 76% reduction in adults aged 75 years and older.
According to the study's authors, these results provide evidence of RSV vaccination's effectiveness against hospitalization, offering additional data beyond prior trial findings. The study also showed the vaccine's effectiveness in reducing RSV-related hospitalizations in high-risk populations, including older adults and those with immunocompromising conditions. However, low vaccine uptake and the potential for residual confounding may affect generalizability. Continued evaluation of vaccine effectiveness in future seasons is necessary to validate these findings and assess the duration of vaccine effectiveness.
In response to these findings, the CDC updated its RSV vaccination guidance in June 2024, recommending a single dose of the RSV vaccine for all adults aged 75 years and older, as well as for those aged 60 to 74 years at increased risk of severe RSV infection.
This study was funded by the CDC, and some authors reported receiving grants and contracts from the CDC and other agencies.
