RSV Immunization Extended Nationally as Season Shifts; Utah Leads in Infant Protection
Most U.S. states have extended their Respiratory Syncytial Virus (RSV) immunization period for infants and toddlers through April 30. This decision comes as the virus continues to spread later into the spring than typically observed. Concurrently, Primary Children's Hospital in Salt Lake City, Utah, has reported a decrease in infant RSV admissions over the past two years, a trend attributed to increased vaccination efforts. Utah is notably a national leader in maternal RSV vaccination rates.
Shifting RSV Seasonality Prompts National Action
RSV, a common respiratory virus, typically emerges in the fall, peaks in winter, and subsides by spring. However, this season has presented an unusual pattern. Federal data for the third week of March indicated a 7.5% RSV test positivity rate, significantly higher than the 5% rate recorded at the same time last year. This sustained late-season activity has spurred public health officials into action.
In response to these trends, the U.S. Centers for Disease Control and Prevention (CDC) advised states in mid-March to review their local RSV data. Subsequently, 48 jurisdictions, encompassing states and major cities, have extended their RSV immunization periods through at least April 30. This extension facilitates continued ordering of immunizations through the federal Vaccines for Children program and encourages healthcare providers to maintain robust immunization efforts.
Dr. Susan Kansagra, chief medical officer for the Association of State and Territorial Health Officials, highlighted that RSV peaked later this year, leading to ongoing emergency department visits and hospitalizations in numerous regions. Experts are currently investigating environmental, biological, and behavioral factors that might contribute to this shifted seasonality.
"Public health responses should be based on current disease trends rather than fixed calendars."
— Dr. Jennifer Nuzzo, Epidemiologist
While most jurisdictions extended their periods, ten — including Florida, Hawaii, and Oregon — either experience year-round RSV seasons or had local epidemiological data that did not necessitate an extension. Louisiana and Washington, D.C., chose not to extend, while Missouri and Virginia will review provider orders on a case-by-case basis.
The U.S. Department of Health and Human Services (HHS) continues to recommend that infants born to mothers who did not receive the vaccine should receive one dose of the antibody shot. Despite existing data affirming their safety and efficacy, U.S. health regulators have also initiated inquiries into the RSV shots.
Understanding RSV Immunization
Immunization against RSV is accessible through several crucial avenues:
- Maternal Vaccination: Pregnant individuals can receive the Abrysvo vaccine during their third trimester. This vaccine facilitates the transfer of protective immunity to their babies within two weeks of birth.
- Infant Monoclonal Antibodies: Babies born during the RSV season can be immunized shortly after birth with Nirsevimab monoclonal antibodies, which offer protection within days.
- Pediatrician Visits: For infants born between April and September (outside the typical RSV season), families are encouraged to seek vaccination from their pediatrician.
A CDC study published last year provided encouraging news, finding that RSV-associated hospitalization rates among infants up to seven months old during the 2024-25 season were lower than in previous seasons before these immunizations became widely available. This marks the third season that monoclonal antibodies have been widely accessible for RSV protection.
RSV can be particularly severe for infants, causing bronchiolitis that can impair breathing and eating, and potentially disrupt development.
The CDC reports that two to three out of every 100 infants younger than three months are hospitalized with RSV annually in the U.S. Tens of thousands of children have been hospitalized with RSV this season, underscoring the virus's significant impact on young children.
Utah's Proactive Strategy and Positive Results
Intermountain Health reports that Utah leads the nation in protecting babies against RSV, with twice as many expectant mothers choosing vaccination before birth compared to the national average. This proactive approach has coincided with a notable decrease in infant admissions for RSV at Primary Children's Hospital over the past two years.
Dr. Per Gesteland, director of acute care services for Intermountain Children's Health, observed that the reduced severity of the RSV season has significantly decreased stress on the healthcare system by lowering intensive care admissions. Carolyn Reynolds, executive director of the ambulatory clinical program at Intermountain Children's Health, noted that Intermountain Health accelerated the deployment of RSV vaccines, prioritizing extensive educational efforts throughout 2024 and 2025, despite a scaled-back campaign in 2023 due to supply issues.
An Intermountain Health study revealed compelling local data: for unimmunized infants in Utah, one in 48 are hospitalized with RSV in their first year, and one in 200 require intensive care. For immunized infants, these figures dramatically decrease to one in 400 hospitalized and one in 1,000 in the ICU.
National studies corroborate the safety and effectiveness of the RSV vaccine, with local data strongly supporting its positive impact.