Vaccinating pregnant women against respiratory syncytial virus (RSV) can reduce hospitalisations in infants by around 80%, according to new research.
A large real-world study in Scotland found that babies under three months old whose mothers received the RSV vaccine were far less likely to be hospitalised compared with babies of unvaccinated mothers. Premature infants, who are at highest risk from RSV, also benefited significantly when their mothers were vaccinated.
Researchers working with Public Health Scotland (PHS) reported that since the programme began in August 2024, 219 fewer infants were admitted to hospital with severe RSV during the winter season, despite RSV circulation levels being similar to the previous year. The findings were published in The Lancet Infectious Diseases.
RSV is a seasonal virus that poses a serious risk to young babies. Since August 2024, all pregnant women in Scotland have been offered the vaccine at 28 weeks, allowing them to pass protective antibodies to their unborn child. Similar vaccination programmes were launched in September 2024 in England, Wales, and Northern Ireland.
The study used a retrospective nested case-control design, including all singleton births in Scotland between August 2024 and March 2025. Researchers analysed maternal vaccination records alongside infant hospitalisation data to identify babies admitted with lower respiratory tract infections who tested positive for RSV. Each case was matched with ten control infants who were not hospitalised with RSV during the same period.
Babies were grouped based on the timing of maternal vaccination. Full protection was defined as mothers vaccinated more than 14 days before birth, while sub-optimal protection applied to those vaccinated within two weeks of delivery. Babies born to unvaccinated mothers received no protection.
The results show that maternal vaccination provides the highest levels of infant protection. Babies of vaccinated mothers had roughly an 80% lower risk of RSV-related hospitalisation in their first three months. Vaccination at 28 weeks or later is recommended to ensure maximum antibody transfer; mothers vaccinated less than 14 days before delivery did not pass sufficient protection.
Before the vaccination programme in 2023-24, nearly 600 infants under three months were hospitalised with severe RSV in Scotland. Following the rollout, the reduction in RSV cases prevented an estimated 219 hospital admissions over the winter season.
Professor Antonia Ho, Professor of Infectious Diseases at the University of Glasgow, said: “This study shows that maternal vaccination can reduce the risk of RSV-related hospital admissions by around 80% in the first three months of life. We hope these results will encourage more women to take up the vaccine to protect their babies and ease the burden on health services during winter.”
In August, England’s chief midwifery officer urged eligible pregnant women to get vaccinated against RSV ahead of the winter as case numbers continued to rise.
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