FDA Approves Pfizer’s RSV Vaccine for Older Adults

Pictured: Syringe pulling vaccine from a vial / Adobe Stock, weyo

Pictured: Syringe pulling vaccine from a vial / Adobe Stock, weyo

The FDA has approved Pfizer’s respiratory syncytial virus vaccine, henceforth to carry the brand name Abrysvo, to prevent lower respiratory tract disease in older adults aged 60 years and above, the company announced Wednesday.

Abrysvo’s approval comes nearly a month after GSK won the FDA’s first-ever nod for its RSV shot Arexvy. Both Pfizer and GSK faced the regulator’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) in March 2023, leading to favorable votes supporting both vaccines’ benefit-risk ratio.

Abrysvo's label carries precautions for adverse events such as fatigue, headache and injection site pain. Moreover, during the panel deliberations, the VRBPAC flagged two cases of Guillain-Barré syndrome (GBS) out of 19,942 vaccinated participants.

As a result, the FDA has requested Pfizer conduct a pharmacovigilance process to track GBS cases, as well as a post-marketing safety study for its RSV shot.

“Pfizer has robust processes to meet post-authorization responsibilities to closely monitor all potential adverse events and collect relevant information to assess any new potential safety risks that may be associated with the vaccine,” a Pfizer spokesperson said in an email to BioSpace.

Data from the Phase III RENOIR study formed the basis for Abrysvo’s approval. With some 37,000 participants enrolled, the randomized, double-blinded and placebo-controlled trial found the vaccine was 66.7% effective at preventing RSV-associated lower respiratory tract disease (LRTD) with at least two signs and symptoms.

For infection-related LRTD with at least three signs or symptoms, Abrysvo demonstrated an 85.7% vaccine efficacy rate.

RENOIR is ongoing and more efficacy data are expected after the study’s second RSV season.

Race for Pediatric Shot

While Pfizer has fallen slightly behind GSK in the race to develop an RSV vaccine for older adults, the New York-based company is a frontrunner in the pediatric setting.

In April, Pfizer published data from its Phase III MATISSE trial, showing that at 90 and 180 days after birth, its RSV vaccine candidate was 81.8% and 69.4% effective at reducing medically-attended severe RSV-associated LRTD, respectively. However, MATISSE missed its second primary endpoint of medically-attended RSV-associated LRTD.

These data were published in the New England Journal of Medicine.

In May, Abrysvo won the backing of the FDA’s VRBPAC, earning a unanimous vote for its efficacy data and a 10 to 4 vote for its safety. Overall, the independent panel of experts deemed that maternal inoculation with Abrysvo for infant immunization had a favorable benefit-risk profile.

MATISSE was part of Pfizer’s data package for its pediatric bid for Abrysvo, along with four other clinical trials consisting of a total of more than 4,100 pregnant mothers that were given the vaccine candidate.

If approved for pediatric use, Abrysvo could become the first maternal shot meant to protect infants from RSV “at first breath through their first six months of life,” Annaliesa Anderson, Pfizer’s chief scientific officer for vaccine research and development, said at the time of the VRBPAC vote.

The FDA is set to release its decision in August.

Tristan Manalac is an independent science writer based in metro Manila, Philippines. He can be reached at tristan@tristanmanalac.com or tristan.manalac@biospace.com.

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