The following is a summary of “Respiratory syncytial virus vaccine effectiveness among US veterans, September, 2023 to March, 2024: a target trial emulation study,” published in the January 2025 issue of Infectious Disease by Bajema et al. 

Researchers conducted a retrospective study to examine the real-world effectiveness of newly approved respiratory syncytial virus (RSV) vaccines in preventing RSV-associated lower respiratory tract disease in adults aged 60 and older.  

They used electronic health records from the Veterans Health Administration to simulate a target trial comparing a single dose of recombinant stabilised prefusion F protein RSV vaccine to no vaccination among veterans aged 60 and older. Eligible vaccine recipients were matched with up to 4 unvaccinated individuals in 4 monthly nested sequential trials from September 1 to December 31, 2023. Outcomes were followed until March 31, 2024. The primary outcome was any positive RSV test from day 14 following the matched index date. Secondary outcomes included hospitalisation and emergency department or urgent care visits within 1 day before or after a positive RSV test. Vaccine effectiveness was estimated as 100 × (1 − risk ratio).  

The results showed 1,46,852 vaccinated individuals were matched to 5,82,936 unvaccinated controls of the 2,93,704 veterans, 2,76,039 (94.0%) were male, and 17,665 (6.0%) were female, with a median age of 75.9 years (IQR 71.7–79.7). During a median follow-up of 124 days (IQR 102–150), the incidence of RSV infection was 1.7 (95% CI 1.4–2.1) per 1000 person-years (88 events) in the vaccinated group and 7.3 (6.6–8.1) per 1000 person-years (372 events) in the unvaccinated group. Vaccine effectiveness was 78.1% (72.6–83.5). For secondary outcomes, vaccine effectiveness was 78.7% (72.2–84.8) against RSV-related emergency department or urgent care visits and 80.3% (65.8–90.1) against RSV-associated hospitalisation.  

Investigators concluded the RSV vaccination prevented RSV-related illness and associated healthcare utilization in older adults (OAs) during the 2023-24. 

Source: thelancet.com/journals/laninf/article/PIIS1473-3099(24)00796-5/abstract