RSV Vaccine Effective in Older Veterans in preventing infection, reveals research
A new study published in the Journal of American Medical Association showed that veterans, 60 years of age and older who got a single dose of the RSVPreF3 or RSVpreF vaccine showed superior protection against respiratory syncytial virus (RSV) infection across two respiratory seasons.
For older individuals and those who are more susceptible to severe respiratory syncytial virus, a single dose of the vaccination is advised. The long-term efficacy of RSV vaccinations requires clinical data. Thus, this study evaluated the efficacy of RSV immunization during two seasons of respiratory disease.
Veterans 60 years of age and older who qualified for RSV vaccine between September 2023 and March 2024 were included in this target trial simulation, which used data from the Veterans Health Administration. The participants received either no RSV immunization or a single dose of a recombinant stabilized prefusion F protein RSV vaccine. From September 1, 2023 to March 31, 2024, 7 monthly nested sequential trials were conducted, matching eligible vaccination recipients with up to 4 unvaccinated persons.
The results were determined up until March 31, 2025. Any positive RSV test result from day 14 after the matching index date was the main consequence. RSV-related ER or urgent care visits, hospital stays, or critical care unit admissions were secondary outcomes. The anticipated efficacy of the vaccine was 100 x (1 – risk ratio).
Following up for a median of 15.8 months (IQR, 14.5-17.0), a total of 288 111 vaccinated people were matched to 1 075 893 unique control individuals, weighted equally to represent 576 222 individuals. In both groups, the median age was 76.1 years (IQR, 71.6-80.0), and 544 364 of 576 222 veterans (94.5%) were men. Over a follow-up period of 0 to 18 months, vaccine efficacy against recorded RSV infections dropped from 82.5% (95% CI, 77.5%-86.9%) to 59.4% (95% CI, 55.6%-63.5%).
Effectiveness dropped from 84.9% (95% CI, 78.4%-90.2%) to 60.5% (95% CI, 56.4%-65.7%) for emergency visits, from 88.9% (95% CI, 77.9%-95.7%) to 57.3% (95% CI, 47.3%-66.4%) for hospitalizations, and from 92.5% (95% CI, 61.1%-100.0%) and 71.9% (95% CI, 42.8%-90.0%) for intensive care unit admissions. Protection against recorded infections dropped from 75.2% (95% CI, 52.5%-89.3%) to 39.7% (95% CI, 23.9%-52.7%) in immunocompromised people.
Overall, although protection decreased over time and varied by risk category, veterans 60 years of age and older who received a single dose of the RSVPreF3 or RSVpreF vaccine were better protected against RSV infection across two respiratory disease seasons than unvaccinated adults in this trial emulation cohort study.
Reference:
Bajema, K. L., Bui, D. P., Yan, L., Li, Y., Rajeevan, N., Vergun, R., Sriskantharajah, V., Hynes, D. M., Berry, K., Huang, Y., Lin, H.-M., Aslan, M., & Ioannou, G. N. (2025). Durability of respiratory syncytial virus vaccine effectiveness among US veterans. JAMA Internal Medicine. https://doi.org/10.1001/jamainternmed.2025.6355
