FDA Reviews GSK’s Arexvy RSV Vaccine for Adults Aged 18-49 at Risk

On July 14, 2025, GlaxoSmithKline (GSK) plc announced that the U.S. Food and Drug Administration (FDA) accepted its application to review the expanded use of Arexvy, a vaccine designed to prevent respiratory syncytial virus (RSV) infections, for adults aged 18 to 49 who exhibit increased risk factors. This decision comes at a time when more than 21 million adults under the age of 50 in the United States have at least one risk factor for severe RSV infection, including chronic obstructive pulmonary disease (COPD), asthma, and coronary heart disease.

The FDA’s review is based on positive results from a Phase IIIb clinical trial, which demonstrated the safety and immune response of Arexvy in the targeted demographic. GSK's vaccine is already approved for use in adults aged 60 and older, as well as for those aged 50-59 with increased risk. The expected FDA decision regarding the expanded indication is anticipated in the first half of 2026.

RSV is a common viral infection that significantly impacts the lungs and respiratory system, affecting an estimated 64 million individuals worldwide annually. According to the National Institute of Allergy and Infectious Diseases, adults can experience severe complications from RSV, especially those with pre-existing health conditions.

Dr. Tony Wood, GSK's Chief Scientific Officer, stated, "The acceptance of this application by the FDA reflects our commitment to addressing public health needs, particularly for vulnerable populations. We believe that Arexvy can play a crucial role in preventing severe RSV disease among adults under 50 who are at increased risk."

The Phase IIIb trial, referenced as NCT06389487, involved 1,458 participants across 52 locations in six countries, including 16 sites in the U.S. The trial's co-primary endpoints included measuring the immune response and safety profiles compared to older populations. Preliminary findings indicated that the vaccine's safety and reactogenicity were consistent with previous studies.

GSK's RSV vaccine employs a recombinant RSV glycoprotein F, stabilized in its prefusion conformation, combined with the proprietary AS01E adjuvant system. This combination is believed to enhance the immune response against the virus, providing protection to at-risk adults.

As the FDA initiates its review process, GSK is also pursuing expanded indications for Arexvy in international markets, including the European Economic Area and Japan. The growing recognition of RSV's impact on adult health underlines the significance of GSK's application and the potential benefits of Arexvy in reducing RSV-related morbidity and mortality.

In conclusion, the upcoming decision by the FDA represents a pivotal moment for GSK and public health stakeholders, as the expanded use of Arexvy could significantly enhance preventive measures against RSV for millions of high-risk adults in the U.S. The implications of this review extend beyond immediate health outcomes, potentially influencing future vaccine development strategies and public health policies regarding respiratory infections.