Real-World Studies Confirm RSV Immunizations Protect Infants from Hospitalization
Real-world studies show nirsevimab reduced RSV infant hospitalizations by up to 72% and maternal vaccination cut hospitalizations by nearly 70%, with benefits extending into the second RSV season.
New real-world studies confirm that recently developed immunizations against respiratory syncytial virus (RSV) protect infants in their first year of life. The research, including studies in France, the United Kingdom, the United States, and Spain, shows that both maternal vaccination and the infant monoclonal antibody nirsevimab substantially reduce RSV-related hospitalizations.
In a nationwide French study of nearly 75,000 infants published in JAMA Pediatrics, newborns immunized with nirsevimab (sold in the United States as Beyfortus) during the 2023–2024 respiratory season were 66% less likely to be hospitalized with RSV. Those immunized during the 2024–25 season were 72% less likely. Nirsevimab provides lab-grown antibodies that protect babies immediately, but the protection lasts only about five months, covering the first respiratory season. The researchers also found a small increase in the risk of hospitalization for ear, nose, and throat infections among immunized infants, but they cautioned the finding was based on a small number of cases and does not outweigh the benefits of RSV immunization.
Two new studies evaluated maternal RSV vaccination. A British study published online in The Lancet Child & Adolescent Health found that babies whose mothers were vaccinated during weeks 28 to 31 of pregnancy were 61% less likely to be hospitalized for RSV in their first six months of life. Newborns under 3 months of age were 76% less likely. A separate U.S. study led by researchers at the University of Pittsburgh and UPMC, published in JAMA Network Open, found that one dose of the maternal RSVpreF vaccine reduced RSV-related hospitalization in young infants by nearly 70%. Among infants younger than 3 months, effectiveness was approximately 68% against RSV-related hospitalization and 69% against severe lung infections caused by the virus. The U.S. study analyzed health records from infants 90 days old or younger hospitalized during the 2023–2024 and 2024–2025 RSV seasons in Western Pennsylvania. The maternal RSV vaccine is recommended between 32 and 36 weeks of pregnancy and typically given between September and January in most of the United States, according to the CDC.
A universal RSV immunization programme with nirsevimab also showed benefits beyond the first RSV season. The NIRSE-GAL study in Galicia, Spain, published in The Lancet Infectious Diseases and presented at the RSVVW '26 conference in Rome, found 55.3% fewer hospitalizations in the second RSV season among infants who had received a dose of nirsevimab during their first season. It is the first prospective real-world population study to evaluate the impact of a universal nirsevimab programme across two consecutive RSV seasons.
RSV remains a major threat to infants: it hospitalizes 1.4 million babies around the world every year, making it the most common cause of hospital admission for respiratory disease in infants, and it kills nearly 46,000 babies under 6 months of age annually, according to the World Health Organization.