Single-Dose RSV Vaccine Shows Sustained Protection in Older Adults
A phase 3 clinical trial has shown that a single dose of the AS01E-adjuvanted respiratory syncytial virus prefusion F protein-based (RSVPreF3 OA) vaccine offers strong and lasting protection against RSV-related lower respiratory tract disease (RSV-LRTD) in adults aged 60 and older over three RSV seasons.
The global AReSVi-006 study involved more than 24 000 participants and was conducted across 275 centers in 17 countries in Africa, Asia, Oceania, Europe, and North America. Participants were randomized to receive either a single dose of the vaccine or a placebo before the first RSV season. Vaccine recipients were further re-randomized before the second season to either receive a second dose or placebo, allowing researchers to compare the durability of a single dose with a revaccination strategy.
Results demonstrated a cumulative efficacy of 62.9% (97.5% CI 46.7-74.8) against RSV-LRTD over three seasons in the single-dose group. The vaccine also showed subtype-specific protection: 69.8% efficacy against RSV A-related LRTD and 58.6% against RSV B-related LRTD. Efficacy was observed across key subgroups, including individuals aged 60 to 69 and 70 to 79, as well as those who were pre-frail or had pre-existing health conditions that increased their risk of severe RSV illness.
While a decline in efficacy was noted over time, vaccinated individuals remained significantly more protected than those receiving placebo even in the third season. The revaccination strategy—administering a second dose one year after the first—yielded similar efficacy levels to the single-dose regimen.
The vaccine was well tolerated, with serious adverse events occurring in fewer than 1% of participants across all study arms. Five deaths were deemed potentially related to the trial intervention: three in the vaccine group and two in the placebo group. However, the researchers note that further investigation is needed to determine the optimal revaccination schedule to ensure durable protection.
Reference
Ison MG, Papi A, Athan E, et al. Efficacy, safety, and immunogenicity of the AS01E-adjuvanted respiratory syncytial virus prefusion F protein vaccine (RSVPreF3 OA) in older adults over three respiratory syncytial virus seasons (AReSVi-006): a multicentre, randomised, observer-blinded, placebo-controlled, phase 3 trial. Lancet Respir Med. 2025;11:S2213-2600(25)00048-7. doi: 10.1016/S2213-2600(25)00048-7
