RSV Vaccine Protection Waned Over Two Seasons
A study of 288,111 veterans found that RSV vaccine effectiveness declined significantly within 18 months of administration.
Updated on Sept. 24, 2026 in Asthma
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A VA study concluded on March 31, 2025, revealed that RSV vaccine protection decreases over two seasons, with effectiveness dropping from 82.5% to 59.4% over 18 months. The findings indicate a sharper decline among immunocompromised patients and older adults.
Why it matters
The findings highlight a potential need for future vaccination strategies, as the waning protection could leave vulnerable older populations at risk of RSV-related complications. Researchers are now working to determine if revaccination is necessary and which groups would benefit most.
A target trial emulation analysis of 288,111 vaccinated veterans showed that effectiveness against RSV hospitalizations fell from 88.9% to 57.3% over 18 months. The vaccine, which costs approximately $350 per dose, showed a median participant age of 76.1 years.
The players
VA Portland Health Care System
This facility provided the institutional framework for the research conducted on veteran health outcomes.
Oregon Health & Science University
This academic institution supported the research team in performing the target trial emulation analysis.
The details
Researchers performed a target trial emulation by matching vaccinated veterans with up to four unvaccinated controls to track outcomes over 18 months. The analysis recorded significant drops in protection against various outcomes, including emergency visits, hospitalizations, and ICU admissions.
Timeline
Enrollment of study participants began on September 1, 2023.
Enrollment of study participants concluded on March 31, 2024.
The follow-up period for study participants concluded on March 31, 2025.
The Big Picture
This study follows a pattern set by the VA's longitudinal veteran health surveillance program to track long-term medical intervention outcomes. The findings necessitate a re-evaluation of current immunization schedules to account for long-term efficacy decay.
Patients who received the RSV vaccine should discuss their individual risk profile and protection status with a healthcare provider given the observed decline in efficacy. This may influence decisions regarding the timing of future preventive measures for those aged 80 and older.
The takeaway
The data underscores that RSV vaccine protection is not indefinite, particularly for older and immunocompromised individuals. Patients should consult with their physicians about the duration of their vaccine immunity to ensure they remain adequately protected during peak RSV seasons.
Further reading
For more on respiratory health, visit the Asthma section.
Source note: This article includes information reported by Medscape.
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