RSV is still spreading, prompting states to extend the immunization period

Key Points:

• Respiratory syncytial virus (RSV) is spreading later into spring than usual, prompting most US states to extend the immunization period for eligible infants and toddlers through the end of April instead of March.
• Federal data shows a higher RSV test positivity rate (7.5%) in mid-March compared to previous years, with ongoing emergency visits and hospitalizations driving health departments to recommend continued monoclonal antibody administration.
• Monoclonal antibodies, available for only three seasons, significantly reduce RSV hospitalizations in infants, and the American Academy of Pediatrics recommends their use alongside a maternal vaccine to protect young children.
• As of late March, 48 US jurisdictions extended RSV immunization periods, while some states like Louisiana and Washington, D.C., opted not to; the timing shift in RSV season is not fully understood but may relate to environmental and behavioral factors.
• Experts emphasize the importance of data-driven responses and real-time surveillance to adjust immunization availability according to actual disease trends rather than fixed calendar schedules.