A new UK Health Security Agency (UKHSA) study shows the maternal respiratory syncytial virus (RSV) vaccination programme is providing over 80% protection for newborn infants, including those born prematurely.
The study – Maternal RSV vaccination and reduced risk of hospitalisation for babies in England 2024/25 - found vaccination at least two weeks before the birth gave 81.3% protection. A narrow range of statistical uncertainty, 78.9% to 83.4%, means there is high confidence in the protective effect of the vaccine.
Analysing data from the first year of vaccine roll out (24/25), the study is believed to be the largest in the world evaluating the effect of maternal RSV vaccination in preventing infants being hospitalised for RSV chest infection. RSV causes bronchiolitis (infection and inflammation of the small airways of the lung) and is a major cause of hospital admission in infants. The maternal vaccination programme is offered to women from 28 weeks of pregnancy to protect newborns.
Nearly 300,000 babies born between September 2024 and March 2025 were followed, representing around 90% of all births in England during this period. Using routinely collected electronic health records, UKHSA researchers assessed the vaccine’s effectiveness in preventing hospital admissions. More than 4,500 hospitalisations occurred in this cohort, the vast majority in infants whose mothers had not been vaccinated.
Getting the vaccine on time was best (in week 28 or soon after that), as babies born at least four weeks after their mother was vaccinated had nearly 85% protection. But importantly, even vaccination later in pregnancy still gives some protection, with vaccination as close as 10 to 13 days before birth reducing hospital admissions by 50%.
The study, which was on 18 April at the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) global conference, also found that premature babies, who are particularly vulnerable to RSV, can be well protected, provided there is at least two weeks between vaccination and birth.
Matt Wilson, Epidemiologist at UKHSA, presenter and lead author, said: “Our evaluation of the first season of the programme in England gives important confirmation that maternal RSV vaccination is highly protective for newborn infants, over 80%, and that effectiveness reached nearly 85% when vaccination occurred at least four weeks before birth. These findings are also particularly important for preterm infants, who are among the most vulnerable to severe RSV infection. With sufficient time between vaccination and birth, we saw good levels of protection in these babies. Giving the vaccination early in the third trimester, as recommended by the World Health Organization, could protect most preterm infants, so it’s important that midwives and other healthcare workers offer vaccination on time with the schedule – and that pregnant women take it up promptly.”
Maternal RSV vaccine uptake in England continues to climb, reaching 55% during the study period and the latest data showing uptake rising to 64.1% for women who gave birth in November 2025.