FDA Approves Abrysvo to Prevent Respiratory Syncytial Virus in Older Adults

The FDA has approved Pfizer Inc’s bivalent respiratory syncytial virus (RSV) prefusion F (RSVpreF) vaccine Abrysvo to prevent lower respiratory tract disease caused by RSV in individuals 60 years of age and older. According to Pfizer, RSVpreF is based on foundational basic science discoveries, such as findings from the National Institutes of Health (NIH), detailing the crystal structure of prefusion F, a vital form of the viral fusion protein (F) used by RSV to attack human cells. NIH research indicates that antibodies specific to the prefusion form had high efficacy preventing viral infection, which indicates that a prefusion F-based vaccine may provide optimal protection against RSV, according to Pfizer.

“A vaccine to help prevent RSV had been an elusive public health goal for more than half a century. Today’s approval is a monumental step forward in delivering on Pfizer’s commitment to help alleviate the significant burden of RSV in higher-risk populations, which includes older adults,” said Annaliesa Anderson, PhD, senior vice president and chief scientific officer, Vaccine Research and Development, Pfizer, in a press release. “Abrysvo will address a need to help protect older adults against the potentially serious consequences of RSV disease. We are extremely grateful to the clinical trial participants, study investigator teams and our dedicated Pfizer colleagues for their roles in making this vaccine available.”

The approval was based on findings from the phase 3 (NCT05035212) RENOIR (RSV vaccine Efficacy study iNOlder adults Immunized against RSV disease) trial. The global, randomized, double-blind, placebo-controlled study evaluated the efficacy, immunogenicity, and safety of a single dose of RSVpreF in adults 60 years of age and older. The study randomized approximately 37,000 participants to receive RSVpreF 120 μg or placebo in a 1:1 ratio. Pfizer previously announced positive top-line findings from an interim efficacy analysis for RENOIR.

The analysis showed that RSVpreF produced vaccine efficacy of 66.7% (96.66% CI: 28.8%, 85.8%) against RSV-associated lower respiratory tract illness (LRTI-RSV) as defined by 2 or more symptoms. This finding prompted researchers to examine the more severe disease primary endpoint of LRTI-RSV as defined by 3 or more symptoms, which showed an efficacy rate of 85.7% (96.66% CI: 32.0%, 98.7%). Additionally, the trial showed that the investigational vaccine was well-tolerated with no safety concerns, according to Pfizer.

The FDA previously granted RSVpreF with Breakthrough Therapy Designation for this indication in March 2022 and granted Priority Review designation in December 2022.

RSV is a contagious virus and a common cause of respiratory illness that can affect the breathing passages and lungs of infected individuals. Among older US adults, RSV infections account for approximately 60,000–120,000 hospitalizations and 6000–14,000 deaths each year. In US children younger than 5 years of age, RSV infections are responsible for approximately 2.1 million outpatient visits and 58,000–80,000 hospitalizations each year.

The US Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices will meet on June 21, 2023, to evaluate recommendations for the appropriate use of RSV vaccines in older adults. Pending the findings from the meeting, Pfizer said it anticipates supply availability for Abrysvo in Q3 2023 ahead of the anticipated RSV season in the fall.

“This past RSV season demonstrated the serious consequences and potential health risks this virus poses for older adults,” said principal RENOIR investigator Edward E. Walsh, MD, Professor of Medicine, University of Rochester Medical Center, in a press release. “Today’s FDA approval of ABRYSVO recognizes significant scientific progress, and importantly helps provide older adults potential protection against RSV and an opportunity to improve community health by helping prevent the disease.”

Reference

U.S. FDA Approves ABRYSVO™, Pfizer’s Vaccine for the Prevention of Respiratory Syncytial Virus (RSV) in Older Adults. Pfizer. News release. May 31, 2023. https://www.pfizer.com/news/press-release/press-release-detail/us-fda-approves-abrysvotm-pfizers-vaccine-prevention