An RSV vaccine demonstrated 83.3% effectiveness in preventing hospitalization among adults aged 60 and older during the 2024-2025 winter season, according to data published today in the Modern England Journal of Medicine. The trial, conducted with over 131,000 participants, showed a statistically significant reduction in hospitalizations related to respiratory syncytial virus (RSV).
The pragmatic, open-label trial randomly assigned participants to receive either the bivalent RSV prefusion F protein-based vaccine, known as RSVpreF, or no vaccine. Researchers utilized national registries to track hospitalization rates, focusing on RSV-related respiratory tract disease as the primary endpoint. Results indicated three hospitalizations occurred in the 65,642 participants who received the vaccine, compared to 18 hospitalizations in the 65,634 participant control group. This translated to an incidence rate of 0.11 events per 1000 participant-years in the vaccine group versus 0.66 events per 1000 participant-years in the control group (P = 0.007).
The vaccine similarly showed strong efficacy against more severe forms of RSV. Vaccine effectiveness reached 91.7% (95% confidence interval, 43.7 to 99.8) in preventing hospitalization for RSV-related lower respiratory tract disease. Researchers had established a minimum effectiveness threshold of greater than 20% for both the primary and secondary RSV-related endpoints, a benchmark the vaccine surpassed.
Hospitalizations for respiratory tract disease from any cause were also reduced in the RSVpreF group, with 284 hospitalizations compared to 335 in the control group, representing a vaccine effectiveness of 15%. The study’s prespecified success criterion for the primary and RSV-related secondary endpoints was a minimum vaccine effectiveness of greater than 20%.
The findings build on earlier research demonstrating the potential of RSVpreF. A study published in December 2023 in the New England Journal of Medicine reported vaccine efficacy of 68.4% (95% confidence interval, 50.9 to 79.7) against RSV-associated acute respiratory disease in older adults. Updated evidence from October 2025 also highlighted the effectiveness of vaccines against the KP.2 subvariant, showing 68% effectiveness (95% CI, 42 to 82) in a case-control study.
The current trial’s results, published January 8, 2026, add to the growing body of evidence supporting RSV vaccination as a preventative measure for older adults, a population particularly vulnerable to severe complications from the virus. The study did not report on long-term durability of protection or the vaccine’s effectiveness against emerging RSV strains.
