GSK has applied to the US Food and Drug Administration (FDA) to extend use of its respiratory syncytial virus (RSV) vaccine Arexvy to adults under the age of 50 who are at increased risk of the disease.
GSK’s Arexvy is already approved in the US for the prevention of lower respiratory tract disease (LRTD) caused by RSV in adults aged 60 and older, and for those aged 50-59 years who are at increased risk. If the latest regulatory submission is approved by the FDA, the vaccine will have indications in those aged 18 years and above. A decision by the FDA is expected in H1 2026.
GSK’s application is based on a Phase IIIb trial (NCT06389487) that produced comparable results to data from the Phase III programme that supported the initial approval of the vaccine in the US. A single dose of the vaccine in adults aged 18-49 at increased risk of RSV-LRTD elicited robust immune responses that were non-inferior to those observed in adults aged 60 and above.
Safety data was also in line with previous results, with the most common adverse events being local pain, fatigue, muscle ache, and headache, all of which were short-lasting.
The label expansion sought by GSK is a bid to compete with Pfizer and Moderna in the younger age groups of the RSV vaccine market. Pfizer’s Abrysvo and Moderna’s mRESVIA are both approved to prevent LRTD in individuals aged 18 to 59 at increased disease risk.
The broader label coverages for Abrysvo and mRESVIA mean Pfizer and Moderna have made in-roads into GSK’s RSV dominant market share, courtesy of Arexvy’s higher sales in older age groups. Arexvy initially captured a larger market share due to its stronger contracts with retail pharmacies and slightly earlier approval in the US market.
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By GlobalDataThe RSV market is one of the most lucrative in the pharmaceutical industry. Around 64 million people of all ages globally every year are impacted by RSV, a common respiratory virus that causes seasonal infections such as the flu. It is also a leading cause of pneumonia and death in infants and older adults. The global RSV market is set to reach $6.3bn in value by 2030, according to analysis by GlobalData.
US vaccine pressures
Despite vying for RSV market share, all three companies are operating within a highly pressurised vaccine landscape in the US. Revenue for Arexvy, Abrysvo, and mRESVIA in 2024 was significantly impacted by the tightening of US RSV vaccine recommendations, which led to reduced vaccination rates.
FDA approvals do not automatically mean shots enter national immunisation schedules. That is instead recommended by the US Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP).
A brief boost came in April, after the ACIP expanded the eligible at-risk group to people aged 50 and older. However, changes to the panel made by US health secretary Robert F Kennedy (RFK) Jr have ushered in new uncertainty surrounding the future of vaccines in the US.
RFK Jr controversially axed the entire ACIP panel in June, replacing it with well-known vaccine sceptics and individuals lacking vaccine knowledge. The move has cast doubts on how immunisation recommendations will be voted on going forward, with infectious disease experts concerned about the consequences to public health.
