Anne-Marie Rick, M.D., Ph.D., spent her career asking families the question that matters most: will my baby end up in the hospital? Now, a landmark study from her team at the University of Pittsburgh and UPMC offers an answer that could transform infant care across the United States.
The research, published in JAMA Network Open, shows that a single dose of maternal RSV vaccine administered during pregnancy reduces hospitalization risk in infants under three months by approximately 70%—a finding that arrives not a moment too soon. Respiratory syncytial virus (RSV) is the leading cause of hospitalization among infants in America. Each year, two to three out of every 100 babies younger than three months are hospitalized due to RSV, some requiring oxygen support or mechanical ventilation. Until the RSVpreF vaccine received FDA approval in 2023, there was no reliable way to protect healthy newborns from this virus from birth onward.
The University of Pittsburgh team analyzed real-world health records from western Pennsylvania during the 2023–24 and 2024–25 RSV seasons, comparing outcomes in infants 90 days old or younger who were hospitalized for respiratory illness. Researchers identified infants whose mothers had received the vaccine during pregnancy and compared them to those whose mothers had not, excluding infants who received a separate monoclonal antibody protection administered after birth. The findings were striking: among infants younger than three months, maternal vaccination showed approximately 68% effectiveness against hospitalization for RSV-related respiratory illness and 69% effectiveness against more severe lung infections caused by the virus. These results align closely with findings from the vaccine's initial clinical trials.
"We designed this study to focus on what matters most to families: whether their baby might end up in the hospital," Rick explained. The study's impact extends beyond individual families. Each hospitalization carries significant costs for the health system and profound stress for parents. By preventing severe RSV infection during the most vulnerable months of life, maternal vaccination offers protection precisely when infants cannot yet mount their own immune response and when their lungs are most vulnerable to serious damage.
This represents early evidence from real-world U.S. clinical care—a crucial complement to controlled trials. Doctors, families, and policymakers often need to see how interventions perform beyond the laboratory setting, and this Pennsylvania-based analysis provides exactly that grounding. The work is part of a larger, four-year study that will continue tracking patients during the 2025–26 and 2026–27 RSV seasons, expanding analysis to infants up to 180 days old and measuring how protection holds over time across different populations.
Rick and her colleagues recognize that this journey is far from finished. "These kinds of real-world data are critical for helping families, clinicians, and policymakers make informed decisions about how best to protect infants," she noted. As the study expands, it will answer remaining questions about durability and effectiveness across diverse groups—information that will shape how this life-saving intervention reaches families nationwide. For now, the evidence from Pittsburgh sends a clear message: maternal RSV vaccination works, and it works when it matters most.