Single Dose of Arexvy RSV Vaccine Shows 3-Year Protection in Older Adults: Daily Dose

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Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

On April 17, 2025, we reported on a study published in The Lancet Respiratory Medicine that examined the safety and efficacy over 3 respiratory syncytial virus (RSV) seasons of the AS01_E-adjuvanted RSV prefusion F protein-based vaccine (RSVPreF3 OA; Arexvy; GSK) against RSV-related lower respiratory tract disease (RSV-LRTD) in older adults.

The study

Researchers conducted a randomized, observer-blind, placebo-controlled, phase 3 study of 24 972 adults aged 60 years and older between May 25, 2021, and January 31, 2022. Participants were initially assigned randomly 1:1 to receive either RSVPreF3 OA or placebo before the first RSV season. Prior to season 2, RSVPreF3 OA recipients were randomly re-assigned to receive either a second dose (RSV revaccination group) or placebo (RSV single-dose group). Placebo recipients from season 1 also received placebo before season 2.

For the efficacy analyses, researchers included 12 468 RSVPreF3 OA recipients and 12 498 placebo recipients, with median follow-up from day 15 after the first dose of 30.6 months.

The findings

The cumulative efficacy of a single RSVPreF3 OA dose over 3 seasons was 62.9% (97.5% CI 46.7–74.8) against RSV-LRTD, 69.8% (42.2–85.7) against RSV A-related LRTD, and 58.6% (35.9–74.1) against RSV B-related LRTD.

Results also showed consistent efficacy across subpopulations evaluated for the study. The vaccine demonstrated efficacy in adults aged 60–69 years and 70–79 years (70.6%), pre-frail participants (walking speed 0.4–0.99 m/s), and individuals with pre-existing conditions that increase risk for severe RSV-LRTD (64.7–70.1% efficacy). Investigators noted that they were unable to reliably estimate efficacy in participants described as “fully frail” or those aged 80 years and older because of the insufficient number of cases.

The safety profile of RSVPreF3 OA was clinically acceptable throughout the study, authors wrote. Serious adverse events considered related to the intervention by investigators occurred in fewer than 1% of participants across all groups. Five deaths were assessed as intervention-related: 3 in the vaccine groups (cardiopulmonary failure, cardiac arrest, and left ventricular failure) and 2 in the placebo group (death of unknown cause and pulmonary embolism).

Authors' comments

"A single RSVPreF3 OA dose was efficacious against RSV-LRTD over three RSV seasons in people aged 60 years or older, despite a decrease in efficacy over time. Further research is needed to establish the optimal revaccination strategy. These results support the [favorable] benefit–risk profile of RSVPreF3 OA to help protect against RSV-LRTD for at least three RSV seasons."

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