Pregnant Women Who are Vaccinated Against RSV Offer Babies a High Level of Protection Against Hospital Admissions

The earlier during pregnancy a vaccination against RSV is given, the stronger the protection for the baby. In fact, it can reduce hospital admissions by over 70%. Research shows that vaccination of expectant mothers is associated with a decrease in the number of newborns admitted to hospital with severe lung infection. Researchers found that vaccination against respiratory syncytial virus (RSV), which was introduced across the UK in late summer 2024, led to a 72% reduction in hospital admissions of babies with the virus when mothers were vaccinated. The findings are the first to demonstrate the vaccine’s effectiveness in pregnant women in the UK in real-world settings. Vaccinating pregnant women could help limit the number of babies who fall ill in winter, thereby reducing pressure on hospitals, experts say.

How RSV Vaccination During Pregnancy Protects Babies

RSV is a common virus that causes coughs and colds, but can also lead to severe pneumonia, known as bronchiolitis, which can be dangerous for babies, requiring some to be admitted to intensive care. The virus is the most common infectious cause of hospital admissions for infants in the UK and worldwide. Vaccination during pregnancy protects both the mother and the child. Antibodies—proteins that help prevent severe infection by the virus—are produced by the mother in response to the vaccine and passed on to the child, protecting them from severe RSV infection for the first six months after birth.

The research team, led by the Universities of Edinburgh and Leicester, recruited 537 babies in England and Scotland who were admitted to hospital with severe respiratory illness during the winter of 2024-2025, the first season after the vaccine was introduced. 391 of the babies tested positive for RSV. Mothers of babies who did not contract RSV were twice as likely to have been vaccinated before giving birth (41 percent) as mothers of RSV-positive babies (19 percent).

Vaccination more than 14 days before giving birth offered greater protection: The number of hospital admissions fell by 72 percent, compared with 58 percent among infants whose mothers had been vaccinated at any time before giving birth. Experts recommend getting vaccinated as early as possible from the 28th week of pregnancy to achieve the best protection, as this gives the mother more time to build up protective antibodies and pass them on to the baby. However, the vaccine can be administered up until the time of birth.

The Work Highlights the Value of Vaccination

Previous research has found that only half of pregnant women in England and Scotland currently receive the RSV vaccine, even though it is highly effective at preventing serious illness. The findings underscore the importance of raising awareness of the availability and effectiveness of the new vaccine to protect babies, experts say. The study was published in the journal The Lancet Child and Adolescent Health. The research collaboration also involved the universities of Bristol, Oxford, Queen’s University Belfast, UCL, and Imperial College London, as well as 30 hospitals in England and Scotland. The study was funded by the Respiratory Syncytial Virus Consortium (RESCEU) of the Innovative Medicines Initiative (IMI) in Europe, the Wellcome Trust, and the Health Protection Research Unit in Respiratory Infections at the National Institute for Health and Care Research (NIHR) at Imperial College London.

Dr. Thomas Williams, study leader at the Institute for Regeneration and Repair at the University of Edinburgh and pediatrician at the Royal Hospital for Children and Young People in Edinburgh, said: “With the availability of an effective RSV vaccine that has been shown to significantly reduce the risk of hospital treatment in infants in the UK, there is a tremendous opportunity for pregnant women to get vaccinated and protect themselves and their infants from RSV bronchiolitis this coming winter.” Professor Damian Roland, Leicester Hospitals and University and consultant in pediatric emergency medicine, said: “Our work highlights the value of vaccination. In line with the treatment and prevention principle of the NHS 10-year plan, we urge all health systems to consider how they can optimize the rollout of RSV vaccination for mothers.”