RSV Vaccine Maintains Efficacy Across Two Seasons in Seniors

Derick Alison
Derick Alison
6 Min Read

BOSTON – Efficacy of the the respiratory syncytial virus (RSV) vaccine held strong for at least two RSV seasons in older adults, according to the AReSVi-006 study.

The RSV perfusion F protein vaccine (Arexvy) efficacy was 82.1% in protecting against all cases of RSV during the first season versus placebo, reported Michael Ison, MD, of the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland.

“A single dose of RSVPreF3 OA was efficacious against RSV-lower respiratory tract disease in adults 60 years of age or older over 2 full RSV seasons, as well as against severe RSV-lower respiratory tract disease, and in adults with advanced ages and underlying comorbidities,” Ison said in a presentation at the IDWeek annual meeting.

Specifically, there were seven cases among 12,466 people who received the vaccine versus 40 cases among 12,494 people on placebo. In the second year, the vaccine efficacy of the one dose was 67.2%, with 30 cases of RSV in the vaccine group compared with 139 cases with placebo, he noted.

The efficacy of the vaccine at one dose was impressive for preventing cases of severe disease:

  • 1 year: 94.1%, one severe case of RSV in the vaccine group vs 17 in the placebo group
  • 2 years: 78.8%, seven cases vs 48, respectively

However, “revaccination after 1 year did not seem to provide additional efficacy benefit for the overall study population,” Ison said. “The clinical development program will further evaluate persistence of efficacy and the optimal timing for revaccination.”

Vaccine efficacy over 2 years was seen in higher risk, age-based groups, he reported:

  • Ages 60-69: 65.4%, 17 cases in 6,963 people vs 74 cases in 7,981 people in the placebo group
  • Ages 70-79: 74.9%, nine cases in 4,489 vs 55 cases in 4,489, respectively

Vaccine efficacy among patients with comorbidities was 66.7%, while among those deemed to be pre-frail, the efficacy was 73.3%, Ison reported.

Arexvy gained FDA approval in May 2023 based on results from the AReSVi-006 trial.

However, session moderator Rajesh Gandhi, MD, of Massachusetts General Hospital/Harvard Medical School in Boston, called for some caution when interpreting the results.”The data we heard at this session suggest that RSV vaccine efficacy is going to last for more than a season,” he told MedPage Today.

“For now, I am telling my patients that we should wait until we get formal guidance from the CDC Advisory Committee on Immunization Practices ([ACIP] on how frequently to receive the vaccine,” said Gandhi, who was not involved in the study.

He noted that in September, the ACIP recommended the single-dose RSV vaccine for those ages 60 and up, “but we don’t know yet if they are going to recommend it annually or at a greater interval. The data presented here looks promising that the RSV vaccine will provide protection for longer than a single season, which is different from the influenza vaccine, which is a yearly shot.”

In AReSVi-006, about 55% of the participants were ages 60-69, while around 36% were ages 70-79, and about 8% were 80 or older. About 79% of the study population was white. Around 1.5% of the cohort was diagnosed as being frail at trial onset, while about 30% were pre-frail, and around 60% were considered fit.

Participants were randomly assigned to receive the RSV vaccine or placebo at baseline. At the end of year 1, 4,966 of the original group that received the vaccine were inoculated a second time. Another 4,991 people who received one dose were then followed for another 12 months, but were not given a second vaccine dose. From the original placebo group, 10,033 individuals were followed for another year, still on placebo.

For adverse events (AEs) — either at the administration site or systemic — the authors reported that the frequencies of solicited AEs after the second dose were similar to those after the first dose, including erythema, pain, swelling, fatigue, fever, and headache. Most AEs “were mild or moderate and resolved within 2-3 days,” Ison’s group reported.

  • author['full_name']

    Ed Susman is a freelance medical writer based in Fort Pierce, Florida, USA.


The study was supported by GSK Biologicals. Some co-authors are company employees.

Ison disclosed relationships with GSK, Adagio Therapeutics, ADMA Biologics, Adamis Pharmaceuticals, AlloVir, Atea, Cidara Therapeutics, Genentech/Roche, Janssen, Shionogi, Takeda, Talaris, Eurofins Viracor, CSL Behring, Janssen, Merck, Seqirus, UpToDate.

Gandhi disclosed no relationships with industry.

Primary Source


Source Reference: Ison M, et al “Efficacy of one dose of the respiratory syncytial virus (RSV) prefusion F protein vaccine (RSVPreF3 OA) in adults ≥60 years of age persists for 2 RSV seasons” IDWeek 2023.

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