Arexvy was previously authorized in the US for adults aged 60 years and older, as well as for those aged 50–59 with underlying medical conditions that heighten the risk of RSV complications. The expanded indication now covers younger adults with certain chronic conditions. The vaccine is not approved for use during pregnancy.

Addressing an Unmet Need in Younger High-Risk Adults

Although RSV is often perceived as a pediatric illness, it places a substantial burden on adults with comorbidities. In the United States, adults aged 18–49 experience an estimated 17,000 RSV-related hospitalizations annually, alongside hundreds of thousands of emergency department visits and nearly 2 million outpatient encounters. Most severe cases in this age group occur in people with chronic cardiovascular or pulmonary disease, kidney disease, diabetes, obesity, or other conditions that compromise resilience to respiratory infections.

GSK noted that expanding access to vaccination for these individuals could help reduce severe disease and ease strain on healthcare services, particularly during seasonal RSV surges.

Clinical Evidence Supporting the Approval

The FDA’s decision was supported by results from a phase IIIb, open-label immunogenicity study (NCT06389487). This trial demonstrated that adults aged 18–49 with stable chronic conditions mounted an immune response that was not inferior to that seen in adults aged 60 years and older after a single dose of Arexvy. The primary endpoints focused on neutralizing antibody responses against RSV-A and RSV-B strains one month after vaccination.

Efficacy data were drawn from an earlier phase III trial (NCT04886596), which formed the basis of the vaccine’s initial approvals. Across studies, Arexvy showed a consistent safety and reactogenicity profile. The most frequently reported adverse events were localized injection-site pain and short-term systemic symptoms such as fatigue, muscle aches, headache, and joint pain, typically resolving within several days.

Vaccine Composition and Mechanism

Arexvy contains a recombinant RSV glycoprotein F antigen stabilized in its prefusion form (RSVPreF3), a configuration designed to elicit a robust neutralizing antibody response. The antigen is combined with GSK’s AS01E adjuvant system, which enhances immune activation. The AS01 platform includes the QS-21 component, licensed from Agenus.

As with all vaccines, immune protection may vary among recipients, and use should follow national immunization guidelines.

Global Regulatory Status

Beyond the United States, Arexvy has already received approval for adults aged 60 years and older in approximately 70 countries. Many regions, including more than 60 countries worldwide, also authorize its use in adults aged 50–59 who have conditions that increase RSV risk. In the European Economic Area, the vaccine is approved for adults aged 18 years and above, reflecting broader regional strategies for RSV prevention.

GSK continues to pursue regulatory submissions in additional markets as part of its long-term growth and infectious disease prevention strategy.

RSV Burden in Adults

RSV infects an estimated 64 million people globally each year. In adults—particularly those who are immunocompromised, have chronic illnesses, or are older—the virus can worsen existing conditions such as chronic obstructive pulmonary disease, asthma, and heart failure. Hospitalized adults with RSV often experience more severe complications and higher mortality compared with pediatric patients, and the true disease burden is likely underestimated due to limited routine testing in adults.

With the expanded FDA approval, Arexvy may play an increasing role in reducing RSV-related morbidity across a broader adult population.