A single dose of Pfizer’s Abrysvo RSV vaccine maintains 89% efficacy against severe lower respiratory tract disease caused by respiratory syncytial virus in adults aged 60 and older at three-year follow-up — with no significant evidence of waning immunity — according to data from the RENOIR Phase 3 trial published in The New England Journal of Medicine.

RSV: An Underappreciated Threat

Respiratory syncytial virus causes approximately 177,000 hospitalizations and 14,000 deaths annually among US adults aged 65 and older — comparable to the annual death toll from influenza in the same population. Yet until 2023, no approved RSV vaccine existed. RSV was long considered primarily a paediatric disease; its severity in older adults has been systematically underestimated and underreported due to the absence of routine testing.

Three-Year Data

The RENOIR trial enrolled 37,000 adults aged 60 and over across 22 countries. Participants received a single intramuscular dose of Abrysvo or placebo, and RSV-associated lower respiratory tract illness was tracked prospectively. The 3-year analysis found:

  • Efficacy against severe RSV-LRTI: 89.0% (95% CI 82.4–93.4%) — essentially unchanged from the 88.9% reported at 1 year
  • Efficacy against any RSV-LRTI: 74.3%
  • RSV-attributable hospitalisation reduced by 87.2%
  • No safety signals emerged over 3 years; Guillain-Barré syndrome cases were numerically balanced between groups

“Three years of protection from a single dose is extraordinary. We do not see this kind of durability with influenza vaccines. It may be that RSV vaccination — unlike flu — does not need to be annual.”

— Dr. Kathleen Mullane, University of Chicago, infectious disease specialist

The RSV Vaccine Landscape

Three RSV vaccines are now approved for adults aged 60 and over: Abrysvo (Pfizer), Arexvy (GSK), and mRESVIA (Moderna — the first mRNA vaccine for RSV). All three have demonstrated comparable short-term efficacy. The RENOIR 3-year data now provides the strongest durability evidence for any of the three, which may influence clinical guidance on vaccination schedules.

Current Guidelines and Uptake

The CDC’s Advisory Committee on Immunization Practices (ACIP) recommends shared clinical decision-making for RSV vaccination in adults aged 60–74 and a strong recommendation for those 75 and older. Despite this, uptake remains disappointingly low — approximately 22% of eligible older adults have been vaccinated, compared to 70%+ for influenza.

Public health campaigns highlighting RSV’s severity in older adults — and the durability of single-dose protection demonstrated by this 3-year data — are expected to be updated to encourage higher uptake ahead of the 2026–27 winter season.

⚕️ Medical Disclaimer: This article is for informational purposes only. It does not constitute medical advice. Always consult a qualified healthcare professional before making health decisions.