On Friday, the Food and Drug Administration (FDA) gave GSK’s respiratory syncytial virus (RSV) vaccine, Arexvy, an expanded approval. This is a big win for GSK, as it’s been tough for vaccine makers recently. Arexvy was first approved for adults aged 60 and older, then for those aged 50 to 59 with a higher risk of severe RSV disease. Now, it’s approved for about 21 million Americans under 50 who have at least one risk factor for severe disease. This puts Arexvy in competition with Pfizer’s Abrysvo and Moderna’s mResvia, which are also approved for this group. RSV is a common cause of respiratory illness and can be severe in infants, the elderly, and people with weakened immune systems. It leads to about 17,000 hospitalizations, 277,000 emergency department visits, and 1.97 million outpatient visits each year in younger adults, according to GSK. Most hospitalizations involve people with chronic medical conditions. GSK’s head of vaccines and infectious research and development, Sanjay Gurunathan, said this expansion can help address a significant medical need and ease pressure on the healthcare system. GSK was the first to get an RSV vaccine approved and has held a strong market share. However, sales have been slipping due to falling demand, partly because the Centers for Disease Control and Prevention (CDC) hasn’t endorsed RSV booster shots. Like other vaccine developers, GSK faces slowing sales in the U.S., where the government has taken a more combative stance against immunizations. The FDA has also set stricter guidelines for vaccine approvals. There are signs of a potentially friendlier stance in the future, though. The FDA’s top vaccine official, Vinay Prasad, is leaving the agency, and there are reports that the Trump administration is avoiding more vaccine policy changes. GSK said the approval was based on study data showing Arexvy’s immune response in younger adults was as good as in older individuals, with consistent safety results.