GSK Looks to Push RSV Vaccine to Younger Seniors with New Phase III Data

GSK HQ_iStock, Wirestock

Pictured: GSK office in Poland/iStock, Wirestock

GSK on Wednesday revealed preliminary results from a Phase III trial demonstrating that its respiratory syncytial virus vaccine Arexvy could also elicit immunity in adults aged 50 to 59 years of age.

The British biopharma did not provide detailed data in its announcement but said that it planned to present these results at the U.S. Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) meeting on Wednesday.

The Phase III study showed that when given to adults 50 to 59 years old, Arexvy could induce an immune response that was non-inferior to that in its currently approved respiratory syncytial virus (RSV) vaccine population. This was true for all participants in this younger age group, as well as those who were at higher risk of RSV disease due to certain underlying medical conditions.

Arexvy’s safety and reactogenicity profiles in the trial were also consistent with what had previously been established. The most common adverse events were pain, fatigue and headache, most of which were mild and transient.

The Phase III results point to Arexvy’s “ability to help protect adults aged 50 to 59” who are at higher risk of lower respiratory tract disease caused by RSV infection, GSK CSO Tony Wood said in a statement.

“We will submit these data for regulatory review as quickly as possible with the goal of offering adults in this age group the option of a vaccine for the first time,” Wood said. The company will also present full findings and analysis from the trial at a future medical congress.

Arexvy is the first FDA-approved RSV vaccine in the U.S., winning its regulatory nod in May 2023. However, its current label only allows its use in adults 60 years old and above. Close behind it was Pfizer’s Abrysvo, which was approved a month later and targets the same vaccine population.

However, despite winning the RSV race, GSK said in its second-quarter earnings briefing that it was anticipating lower rollout numbers for Arexvy than what it saw for its blockbuster shingles vaccine Shingrix. Still, the company expects Arexvy inoculations to be a strong growth driver, particularly as the approval came in time for the 2023-2024 RSV season. GSK estimated at the time that some 80 million older adults in the U.S. were up for their first RSV shot.

In August 2023, GSK alleged that Pfizer had violated four patents related to the antigen used in Arexvy. In its lawsuit, filed in a Delaware federal court, GSK alleged that Pfizer’s Abrysvo uses GSK’s protected inventions. The British company is seeking a jury trial as well as monetary damages. Pfizer has denied the allegations and said that it will defend its position.

Tristan Manalac is an independent science writer based in Metro Manila, Philippines. He can be reached at or

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