FDA Approves Pfizer's Abrysvo Vaccine for Older Adults


The FDA's decision to approve Abrysvo was based on data from a Phase 3 clinical trial, RENOIR, demonstrating the RSV vaccine's efficacy, immunogenicity, and safety in adults 60 and older.

Pfizer  (Adobe Stock, unknown)


(Adobe Stock, unknown)

A version of this article first appeared in our sister publication, ContagionLive®.

Yesterday, Pfizer Inc. declared that the US Food and Drug Administration (FDA) gave approval for their respiratory syncytial virus (RSV) vaccine, Abrysvo, to be used by older adults. This endorsement permits the use of Abrysvo in people aged 60 years and older to prevent lower respiratory tract disease caused by RSV.

Pfizer’s Abrysvo vaccine targets both RSV A and B strains with its 2 preF proteins. The FDA has approved Abrysvo based on comprehensive trial data that confirms its safety and efficacy.

“A vaccine to help prevent RSV had been an elusive public health goal for more than half a century," stated Annaliesa Anderson, PhD, senior vice president and chief scientific officer of vaccine research and development at Pfizer. “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.”

With Abrysvo being granted approval, it becomes the second RSV vaccine to be approved after GSK's Arexvy after more than 50 years of working to develop an RSV vaccine. The approval was based on data obtained from a Phase 3 clinical trial (NCT05035212) called RENOIR (RSV vaccine Efficacy study iNOlder adults Immunized against RSV disease). This study is designed to evaluate the efficacy, safety, and immunogenicity of a single dose of the vaccine in adults aged 60 and above. The trial enrolled around 37,000 randomly assigned participants to receive either RSVpreF 120 μg or a placebo in a 1:1 ratio. The study is ongoing, and efficacy data is being collected during the second RSV season.

Edward E. Walsh, MD, Professor of Medicine at the University of Rochester Medical Center and principal investigator of the RENOIR trial, commented, "This past RSV season demonstrated the serious consequences and potential health risks this virus poses for older adults. 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.”

RSV is a virus that spreads easily and causes respiratory illnesses worldwide. It mainly affects the lungs and airways, which can lead to serious health problems and even death. Older adults in the US are especially at risk from RSV, with the severity of the illness increasing with age and the presence of other health issues like asthma, congestive heart failure, or chronic obstructive pulmonary disease (COPD).

For most people who are generally healthy, RSV causes mild symptoms similar to a cold. They usually recover within 2 weeks without realizing they had the virus. Infants and young children, however, are more vulnerable to severe RSV infections. Pfizer is therefore seeking approval to give RSVpreF to pregnant people, to prevent medically attended lower respiratory tract disease (MA-LRTD) and serious MA-LRTD caused by RSV in babies from birth to 6 months old. The maternal vaccine was recently recommended for approval by the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC), and a decision is expected by August 21, 2023.

The CDC Advisory Committee on Immunization Practices (ACIP) will have a meeting on June 21, 2023, to discuss the use of RSV vaccines in older adults. Pending the outcome of this meeting, Pfizer expects Abrysvo to be available in the third quarter of 2023, just in time for the anticipated RSV season this fall. Pfizer also reported positive top-line results earlier this month from a Phase 3 study on the safety and effectiveness of Abrysvo when coadministered with seasonal inactivated influenza vaccine (SIIV) in adults aged 65 and older. Additionally, Pfizer plans to conduct multiple clinical trials to evaluate RSVpreF in healthy children aged 2 to 5 years, children aged 5 to18 years with comorbidities, adults aged 18-60 years with comorbidities, and adults aged 18 years and older who are immunocompromised and at high risk for adverse RSV outcomes.

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