Daijiworld Media Network – New Delhi
New Delhi, Apr 7: Respiratory syncytial virus (RSV) is continuing to circulate later than usual this spring, prompting most US states to extend the immunization window for eligible infants and toddlers. Normally, RSV season peaks in winter and wanes by March, but this year, persistent cases have led authorities to recommend immunizations through the end of April.
Federal data for the third week of March showed 7.5% of RSV tests were positive—higher than the 5% positivity at the same time last year. “RSV peaked later than usual this year, and many areas are continuing to see emergency department visits and hospitalizations linger into spring,” said Dr. Susan Kansagra, chief medical officer for the Association of State and Territorial Health Officials.
RSV, a common respiratory virus, can cause severe illness in young children. Two to three out of every 100 infants under three months are hospitalized annually in the US due to RSV, according to the CDC. Immunization with monoclonal antibodies offers effective protection, with studies showing lower hospitalization rates among infants up to seven months old during the 2024–25 season compared to previous years.
Dr. Michelle Fiscus, pediatrician and chief medical officer for the Association of Immunization Managers, called the RSV immunizations “game-changers,” emphasizing their role in preventing serious disease in babies.
As of late March, 48 US jurisdictions—including most states—had extended RSV immunization through April 30. Some states, such as Florida, Hawaii, and Oregon, maintain year-round RSV immunization, while Louisiana and Washington, D.C., have opted not to extend the period. Missouri and Virginia are handling extensions on a case-by-case basis.
“The bottom line is that response plans should follow actual disease trends rather than a fixed calendar,” said Dr. Jennifer Nuzzo, epidemiologist at Brown University. Real-time surveillance, she noted, is essential for tracking virus circulation and guiding immunization timing.
Health officials stress that this extension is critical for protecting newborns, with approximately 10,000 babies born each day in the US. Extended RSV immunization could prevent hospitalizations and ensure infants remain protected while the virus continues to circulate.