WESTERN PENNSYLVANIA — A study conducted by researchers at the University of Pittsburgh and UPMC found that maternal RSV vaccination reduced the risk of hospitalization for young infants by approximately 68 to 69 percent. This reduction was observed during the 2023 through 2024 and 2024 through 2025 RSV seasons in western Pennsylvania.
The study focused on health records from infants aged 90 days or younger who were hospitalized for respiratory illness in western Pennsylvania during these periods. Researchers compared hospitalization outcomes for infants whose mothers received the RSV vaccine during pregnancy against those whose mothers did not. Infants who had received postnatal monoclonal antibody protection against RSV were not included in this analysis.
Maternal vaccination demonstrated approximately 68 percent effectiveness against RSV-caused respiratory illness hospitalizations. It also showed 69 percent effectiveness against severe RSV lung infections in infants under 3 months old. The U.S. Food and Drug Administration approved the RSVpreF vaccine in 2023.
Anne-Marie Rick, a pediatric physician and researcher, commented on the study's design. "We designed this study to focus on what matters most to families: whether their baby might end up in the hospital." Rick said.
RSV leads to an estimated 2 to 3 hospitalizations per 100 babies younger than 3 months annually in the United States, according to the Centers for Disease Control and Prevention. Severe RSV infections can require oxygen support or mechanical ventilation.
This research is part of a four-year study assessing the effectiveness of the maternal RSV vaccine across multiple seasons. Researchers plan to continue following patients through the 2025 through 2026 and 2026 through 2027 RSV seasons. This expanded analysis will include infants up to 180 days old. Rick said, "We're continuing to follow patients to understand how well this protection holds over time and across different groups."