The U.S. Food and Drug Administration expanded the approved age indication for GSK plc's (NYSE: GSK) AREXVY respiratory syncytial virus vaccine to include adults aged 18 to 49 years at increased risk for lower respiratory tract disease caused by RSV.

AREXVY was previously approved for adults aged 60 and older, and adults aged 50-59 at increased risk. The vaccine is not approved for use in pregnant individuals.

An estimated 21 million adults under 50 in the U.S. have at least one risk factor for severe RSV infection, according to GSK. The annual RSV burden among U.S. adults aged 18-49 includes approximately 17,000 hospitalizations, 277,000 emergency department visits, and 1.97 million outpatient visits.

The FDA's decision was supported by data from a Phase IIIb trial that demonstrated a non-inferior immune response in the 18-49 age group compared to adults aged 60 and above. The study enrolled 1,458 participants across 52 locations in six countries, including 16 U.S. sites.

The safety profile remained consistent with previous studies, with the most common adverse events being injection site pain, fatigue, muscle pain, headache, and joint pain within four days of vaccination.

"This age expansion can help address a significant medical need for adults in the United States at higher risk of severe RSV disease due to certain underlying conditions," said Sanjay Gurunathan, GSK's head of vaccines and infectious diseases research and development.

AREXVY has been approved for RSV prevention in individuals 60 and older in 70 countries. The vaccine is approved for adults aged 50-59 at increased risk in more than 60 countries, and for adults aged 18 and older in the European Economic Area.