Abrysvo Demonstrates Continued Efficacy in Older Adults Through Second RSV Season

Drug Topics JournalDrug Topics April 2024
Volume 168
Issue 03

Pfizer's RSV vaccine received FDA approval on May 31, 2023.

Pfizer’s respiratory syncytial virus (RSV) vaccine Abrysvo remains efficacious in preventing RSV-associated lower respiratory tract disease in adults aged 60 years and older through 2 full RSV seasons, according to topline study data shared by the manufacturer.1

Data were gathered as part of the ongoing phase 3 RENIOR clinical trial (NCT05035212).

“We are encouraged by the level of protection that we observed after 2 full RSV seasons for Abrysvo,” said Annaliesa Anderson, PhD, senior vice president and chief scientific officer, vaccine research and development at Pfizer, in a press release.1 “This new data indicate that broad and durable protection against both types of RSV that cause disease…is the potential benefit to having a bivalent vaccine.”

RSV vaccine | image credit: MargJohnsonVA - stock.adobe.com

RSV vaccine | image credit: MargJohnsonVA - stock.adobe.com

Study results showed that vaccine efficacy of Abrysvo against RSV-associated lower respiratory tract disease, defined by the presence of 3 or more symptoms, was 77.8% (95% CI, 51.4-91.1) in season 2; efficacy in season 1 was 88.9% (95% CI, 53.6-98.7), demonstrating a “durable efficacy” of 80% or more after 2 RSV seasons. Efficacy was also consistent across seasons in less severe lower respiratory tract disease, which was defined by the presence of 2 or more symptoms (65.1% to 55.7% in season 1 and 2, respectively).

No new reports of adverse events were made during the second RSV season; Pfizer continues to conduct postmarketing studies and surveillance programs to further build out the safety profile of the vaccine.

Pfizer plans to submit these new data to both regulatory authorities and scientific journals for publication.

READ MORE: 2023 Vaccine Approvals

Initial approval of Abrysvo was granted by the FDA in May 2023 for the prevention of RSV-associated lower respiratory tract disease in adults aged 60 years or older, following a decision by the FDA to announce a Breakthrough Therapy Designation for the vaccine. Data supporting the approval—also from the RENIOR clinical trial—were published in the New England Journal of Medicine. At that time, the study had enrolled approximately 37,000 participants who were randomly assigned 1:1 to receive either Abrysvo or a placebo vaccine.2,3

Shortly after approval, the CDC’s Advisory Committee for Immunization Practices (ACIP) recommended the vaccine for use in adults aged 60 years and older.

In August 2023, the vaccine received FDA approval for the prevention of RSV-associated lower respiratory tract disease and RSV-associated severe lower respiratory tract disease in infants from birth through age 6 months through the immunization of pregnant individuals between 32- and 36-weeks gestational age. Another ACIP recommendation followed for maternal immunization.

Abrysvo was also granted marketing authorization by the European Medicines Agency in August 2023.

Two additional clinical trials of Abrysvo are currently underway: The first trial is evaluating vaccine efficacy in children aged 2 to 18 years at higher risk for RSV; the second trial is evaluating efficacy in two groups of adults: adults aged 18 to 59 years who are at higher risk for RSV due to underlying medical conditions such as asthma, diabetes, and chronic obstructive pulmonary disease, and adults aged 18 years and older who are immunocompromised and at high risk for RSV.

READ MORE: Respiratory Resource Center

  1. Pfizer announces positive top-line data for full season two efficacy of abrysvo for RSV in older adults. News release. Pfizer. February 29, 2024. Accessed March 1, 2024. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-announces-positive-top-line-data-full-season-two
  2. US FDA approves Abrysvo, Pfizer’s vaccine for the prevention of respiratory syncytial virus (RSV) in older adults. News release. Pfizer. May 31, 2023. Accessed March 1, 2024. https://www.pfizer.com/news/press-release/press-release-detail/us-fda-approves-abrysvotm-pfizers-vaccine-prevention
  3. Walsh EE, Marc GP, Zareba AM, et al, for the RENOIR Clinical Trial Group. Efficacy and safety of a bivalent RSV prefusion F vaccine in older adults. N Engl J Med. 2023;388:1465-1477. doi:10.1056/NEJMoa2213836
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