Sustained Protection of Bivalent RSV Vaccine for Seniors

TOPLINE:

In a recent final analysis of a phase 3 trial, the b ivalent respiratory syncytial virus prefusion F (RSVpreF) vaccine maintained high efficacy and a favorable safety profile against RSV-associated lower respiratory tract illness (RSV-LRTI) over two seasons in people aged ≥ 60 years. 

METHODOLOGY:

• Researchers present the final results of a phase 3, randomized trial that assessed the safety and efficacy of the bivalent RSVpreF vaccine among adults aged ≥ 60 years recruited from 241 sites across seven countries.
• Participants, including healthy individuals and those with stable medical conditions such as chronic cardiopulmonary disease, were randomly assigned to receive either an intramuscular dose of 120 μg RSVpreF vaccine (n = 18,574) or placebo (n = 18,288).
• The primary objectives were vaccine efficacy (VE) in preventing a first RSV-LRTI episode with at least three severe symptoms and at least two less severe symptoms in the first RSV season post-vaccination and vaccine safety.
• Secondary objectives were to assess VE in preventing a first RSV-LRTI episode with three or more and two or more symptoms and RSV-associated acute respiratory illness (RSV-ARI) in each season and across two seasons.
• Immunogenicity post-vaccination (RSVpreF-elicited immune responses) was evaluated as antibody neutralization titer geometric mean fold rise in a subset of 1067 participants (RSVpreF, n = 537; placebo, n = 530).

TAKEAWAY:

• The VEs were 88.9% (95% CI, 53.6-98.7) and 77.8% (95% CI, 51.4-91.1) against RSV-LRTI with three or more symptoms at the end of seasons 1 and 2, respectively.
• VEs against medically attended RSV with three or more symptoms, medically attended RSV with two or more symptoms, and medically attended RSV-ARI were 76.3%, 60.0%, and 53.2%, respectively.
• Geometric mean fold rise in titers from before to 1 month post-vaccination for RSV-A and RSV-B were 11.6 vs 1.1 and 12.7 vs 1.1 in the RSVpreF vs placebo group, respectively.
• Overall, 1.4% and 1.0% of participants receiving RSVpreF and placebo, respectively, reported adverse events through 1 month post-vaccination, assessed as being related to study intervention. None of the reported deaths were related to RSVpreF or placebo.

IN PRACTICE:

“In this analysis of the global phase 3 RENOIR efficacy study, a single dose of the bivalent RSVpreF vaccine administered to ≥ 60-year-olds maintains high efficacy against RSV-LRTI with a consistent favorable safety profile through 2 complete RSV seasons in the Northern and Southern Hemispheres. RSVpreF also elicited robust neutralizing responses postvaccination that remained well above baseline prevaccination neutralizing titers before the start of the second RSV season through 8-20 months postvaccination,” the authors wrote. 

SOURCE:

This study was led by Edward E. Walsh, MD, University of Rochester Medical Center, Rochester, New York. It was published online on February 10, 2025, in Clinical Infectious Diseases. 

LIMITATIONS:

Immunogenicity analyses were conducted in only a subset of participants, preventing the determination of RSV neutralizing antibody titer levels among those who later developed RSV-associated disease. This study excluded immunocompromised individuals and younger adults with high-risk medical conditions. Additionally, this study was conducted during the COVID-19 pandemic; therefore, factors such as social distancing and masking may have affected case accrual, particularly in the first season.

DISCLOSURES:

This study was supported by Pfizer. One author reported receiving a grant or being an unpaid consultant for Pfizer. Several authors reported being employees of Pfizer and may hold stock or stock options in it. 

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.