A study led by researchers at the University of Pittsburgh and UPMC announced today that JAMA network opena peer-reviewed journal of the American Medical Association, found that vaccination against respiratory syncytial virus (RSV) during pregnancy reduces the infant’s risk of hospitalization by nearly 70%.
This study provides early real-world evidence from clinical practice in the United States showing that administering a single dose of RSV vaccine (RSVpreF vaccine) to mothers reduces RSV-related hospitalizations in infants. This result is consistent with the results of the RSVpreF vaccine clinical trial. The RSVpreF vaccine was approved by the U.S. Food and Drug Administration in 2023.
We designed this study to focus on what matters most to families: whether their baby ends up in the hospital. The findings have significant implications for families and the health care system and highlight how effective this intervention can be at the most vulnerable time in life. ”
Annmarie Rick, MD, lead author of this study, assistant professor of pediatrics and clinical and translational sciences at Pitt School of Medicine, and physician at UPMC Children’s Hospital of Pittsburgh and UPMC McGee Women’s Hospital
Respiratory syncytial virus is the leading cause of infant hospitalization in the United States. According to the Centers for Disease Control and Prevention (CDC), about 2 to 3 out of 100 infants under 3 months of age are hospitalized with RSV each year, and severe cases may require oxygen or a ventilator. Until the approval of the RSVpreF vaccine, there was no reliable way to protect healthy newborns from RSV from birth.
The study analyzed health records of infants 90 days or younger who were hospitalized for respiratory illness in western Pennsylvania during the 2023-24 and 2024-25 respiratory syncytial virus seasons. The researchers focused on infants who were tested for respiratory syncytial virus and compared the results of infants whose mothers received the vaccine during pregnancy with those whose mothers did not. Infants who received monoclonal antibody protection (another RSV prophylaxis option administered after birth) were excluded.
In infants younger than 3 months of age, maternal vaccination was associated with approximately 68% efficacy against hospitalization for respiratory illness caused by RSV and 69% efficacy against more severe lung infections also caused by the virus.
The results are part of an ongoing four-year study to evaluate the effectiveness of maternal respiratory syncytial virus vaccination over multiple seasons. Researchers plan to continue tracking patients during the 2025-2026 and 2026-2027 RSV seasons and expand the analysis to include infants up to 180 days old to assess how long protection lasts.
“We continue to follow patients to understand how effective this protection is over time and across different groups,” Rick said. “Real-world data like this is essential to help families, clinicians, and policy makers make informed decisions about how best to protect infants.”
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Reference magazines:
Rick AM. others. (2026). Maternal respiratory syncytial virus prefusion F vaccination and infant acute respiratory illness. JAMA network open. DOI: 10.1001/jamanetworkopen.2026.16773. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2849945
