Maternal RSV Vaccine Reduces Infant Hospitalizations by 80%

Vaccinating pregnant women against respiratory syncytial virus (RSV) at least two weeks before giving birth reduces the risk of infant hospitalization for severe lung infections by approximately 80%, according to a large UK study presented at the European Society of Clinical Microbiology and Infectious Diseases congress in Munich.

The study analyzed data from 289,399 infants born between September 2024 and March 2025, following the launch of a national RSV vaccination campaign for pregnant women in the UK in September 2024. By December 2024, vaccination coverage reached approximately 55% among pregnant women.

Infants whose mothers received the RSV vaccine at least 14 days before birth had a markedly lower risk of hospitalization, with vaccine effectiveness estimated at 81.3% compared to infants of unvaccinated mothers.

The protective effect increased with longer intervals between vaccination and birth. When vaccination occurred at least four weeks before delivery, effectiveness approached 85%. Even when administered 10 to 13 days before birth, the vaccine still reduced infant hospitalization risk by 50%.

Matt Wilson, lead author and epidemiologist at the UK Health Security Agency, stated that the findings provide robust evidence that maternal RSV vaccination offers substantial protection against severe illness in young infants. He emphasized the clear relationship between timing and protection, noting that effectiveness increases as the interval between vaccination and birth lengthens.

These results align with findings from other recent studies, which also report that maternal RSV vaccination cuts infant hospitalization risk by over 80%. The research supports ongoing public health efforts to prevent RSV, a leading cause of lower respiratory tract infections in infants and a major driver of hospitalizations during early life.