BackgroundRespiratory syncytial virus (RSV) can cause serious illness in older adults. The bivalent RSV prefusion F protein–based vaccine (RSVpreF) has been shown to prevent RSV-associated respiratory illness, but data from randomized trials with regard to its effect on outcomes involving hospitalization are limited.MethodsIn this pragmatic, open-label trial with individual randomization, participants who were 60 years of age or older were assigned in a 1:1 ratio to receive the RSVpreF vaccine (the RSVpreF group) or no vaccine (the control group) during the 2024–2025 winter season. Baseline and outcome data were collected with the use of national registries. The primary end point was hospitalization for RSV-related respiratory tract disease. Secondary end points included hospitalization for RSV-related lower respiratory tract disease and hospitalization for respiratory tract disease from any cause. The prespecified criterion for success for the primary end point and RSV-related secondary end points was a minimum vaccine effectiveness of greater than 20%.ResultsOf 131,379 participants who underwent randomization, 131,276 were included in the intention-to-treat population. During follow-up, hospitalization for RSV-related respiratory tract disease occurred in 3 of 65,642 participants in the RSVpreF group and in 18 of 65,634 participants in the control group (0.11 events vs. 0.66 events per 1000 participant-years; vaccine effectiveness, 83.3%; 95% confidence interval CI, 42.9 to 96.9; P=0.007 for minimum effectiveness of >20%). The RSVpreF group also had fewer hospitalizations for RSV-related lower respiratory tract disease than the control group (1 vs. 12; vaccine effectiveness, 91.7%; 95% CI, 43.7 to 99.8; P=0.009 for minimum effectiveness of >20%), as well as fewer hospitalizations for respiratory tract disease from any cause (284 vs. 335; vaccine effectiveness, 15.2%; 95% CI, 0.5 to 27.9; P=0.04 for vaccine effectiveness of >0%). The incidence of serious adverse events was similar in the two groups.ConclusionsAmong adults 60 years of age or older, the RSVpreF vaccine reduced the incidence of hospitalization for RSV-related respiratory tract disease as compared with no vaccine. (Funded by Pfizer; European Union Clinical Trials number, 2024-516600-42-00; DAN-RSV ClinicalTrials.gov number, NCT06684743.)
Lassen et al. (2025) studied this question.