Research indicates that maternal RSVpreF shots significantly reduce hospitalisations from respiratory illnesses in infants up to 90 days old, supporting existing immunisation policies in the US.
Researchers have found that a maternal RSVpreF shot was linked with strong protection against RSV-related hospital care in very young infants, adding fresh real-world evidence to an immunisation strategy already recommended for pregnancy. In a study published in JAMA Network Open, the vaccine was associated with lower rates of both acute respiratory infection and more serious lower respiratory tract disease in babies up to 90 days old.
The analysis was a case-control study carried out within one healthcare system in western Pennsylvania across two RSV seasons, from 2023-24 and 2024-25. It used a test-negative design, a method commonly used in vaccine studies in which infants admitted with respiratory illness are tested for RSV and then grouped according to whether the virus was detected. The researchers included 274 hospitalised infants, of whom 83 tested positive for RSV and 191 did not.
According to the study, 13.3% of the RSV-positive infants had been exposed to maternal vaccination before birth, compared with 37.2% of the RSV-negative group. After adjustment, vaccine effectiveness was estimated at 67.6% against RSV-associated acute respiratory illness hospitalisations and 69.0% against lower respiratory tract disease hospitalisations from birth to 90 days. Protection was highest in the first month of life, when effectiveness against acute respiratory illness hospitalisation reached 74.2%.
The findings come as U.S. health authorities have been urging vaccination in late pregnancy to shield newborns during their most vulnerable weeks. The CDC recommended maternal RSV vaccination in September 2023, saying pregnant people should receive the dose between 32 and 36 weeks’ gestation. ACOG has issued similar guidance, and earlier trial data showed the vaccine reduced the risk of severe infant lower respiratory tract illness after birth. Separate CDC surveillance during the 2024-25 season also found lower RSV hospitalisation rates among infants after the introduction of maternal vaccination and nirsevimab, another preventive option for babies.
Even so, the authors said the new results should be treated as early clinical evidence rather than a final estimate. The study covered a relatively small number of hospitalisations at a single health system, and further follow-up will be needed to refine how well the vaccine works across seasons and infant age groups.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
