Rsv

• Respiratory syncytial virus (RSV) hospitalizations declined 42% in the week ending March 20, 2026, compared to the peak surge in February, according to CDC surveillance data. • The decline follows the introduction of the first RSV vaccines approved for adults over 60 and high-risk populations, with over 8 million doses administered since January. • RSV typically causes severe disease in infants and older adults; the new vaccines represent a major breakthrough after decades of failed vaccine development efforts.

• The FDA approved the first RSV vaccine for infants via maternal immunization on March 18, 2026, allowing pregnant women to receive vaccination in the third trimester to confer passive immunity to newborns. • The approval is based on a Phase 3 trial showing 82% efficacy in preventing severe RSV disease in infants under six months, with passive immunity lasting approximately three months post-birth. • RSV causes approximately 100,000 hospitalizations and 300-400 deaths annually among US infants, making this vaccine potentially transformative for preventing severe respiratory illness in the most vulnerable population.

• The FDA on March 13 expanded approval of GSK's Arexvy RSV vaccine to adults aged 18-49 at increased risk of lower respiratory tract disease. • Phase 3b trial data showed non-inferior immune response in younger adults compared to those 60+, targeting 21 million U.S. adults under 50 with conditions like diabetes or obesity. • RSV causes 17,000 hospitalizations, 277,000 emergency visits, and 2 million outpatient visits yearly in this group, highlighting need for broader protection amid rising cases.