Dramatic Drop in Infant RSV Cases After Maternal Vaccination
By University of Edinburgh
Scientists found that the respiratory syncytial virus (RSV)
vaccine, rolled out across the UK in late summer 2024, was linked to a 72%
decrease in hospitalizations among babies whose mothers received the shot
during pregnancy.
This is the first study to confirm how well the RSV vaccine
works for pregnant women in real-world conditions in the UK.
Health experts say increasing vaccination rates among
expectant mothers could help reduce the number of infants falling seriously ill
each winter, easing the burden on hospitals.
How Maternal Antibodies Shield Newborns
RSV is a widespread virus known for causing cold-like
symptoms, but in babies it can lead to bronchiolitis, a serious lung infection.
In some cases, infants may need to be admitted to intensive care. RSV is the
leading cause of virus-related hospitalizations among babies in the UK and
worldwide.
When a pregnant woman receives the RSV vaccine, her body
produces antibodies (proteins that fight off infection) in response. These
antibodies are passed to the baby through the placenta, offering protection
against severe RSV during the first six months of life.
Winter Trial Reveals Strong Protection
The research team, led by the Universities of Edinburgh and
Leicester, recruited 537 babies across England and Scotland who had been
admitted to hospital with severe respiratory disease in the winter of
2024-2025, the first season of vaccine implementation. 391 of the babies tested
positive for RSV.
Mothers of babies who did not have RSV were two times more
likely to have received the vaccine before delivery than the mothers of
RSV-positive babies – 41% compared with 19%.
Timing of Vaccination Makes a Big Difference
Receiving the vaccine more than 14 days before delivery
offered a higher protective effect, with a 72% reduction in hospital admissions
compared with 58% for infants whose mothers were vaccinated at any time before
delivery.
Experts recommend getting vaccinated as soon as possible
from 28 weeks of pregnancy to provide the best protection, as this allows more
time for the mother to generate and pass on protective antibodies to the baby,
but the jab can be given up to birth.
Urgent Need to Boost Uptake Among Expectant Mothers
Previous research has found that only half of expectant
mothers in England and Scotland are currently receiving the RSV vaccine,
despite its high success at preventing serious illness.
The findings highlight the importance of raising awareness
of the availability and effectiveness of the new vaccine to help protect
babies, experts say.
Nationwide Collaboration and Backing
The study was published on July 18 in the journal The
Lancet Child and Adolescent Health. The research collaboration also
included the Universities of Bristol, Oxford, Queen’s University Belfast, UCL,
and Imperial College London, and 30 hospitals across England and Scotland.
The study was funded by the Innovative Medicines Initiative
(IMI) Respiratory Syncytial Virus Consortium in Europe (RESCEU), the Wellcome
Trust, and National Institute for Health and Care Research (NIHR) Health
Protection Research Unit in Respiratory Infections, Imperial College London.
Experts Call for Stronger Vaccine Campaigns
Dr. Thomas Williams, study lead from the University of
Edinburgh’s Institute for Regeneration and Repair, and Pediatric Consultant at
the Royal Hospital for Children and Young People in Edinburgh, said: “With the
availability of an effective RSV vaccine shown to significantly reduce the risk
of hospitalization in young infants in the UK, there is an excellent
opportunity for pregnant women to get vaccinated and protect themselves and
their infants from RSV bronchiolitis this coming winter.”
Professor Damian Roland from the Leicester Hospitals and
University and Consultant in Pediatric Emergency Medicine, said: “Our work
highlights the value of vaccination and in keeping with the treatment to
prevention principle of the NHS 10 Year plan, we would ask all health care
systems to consider how they will optimize the roll out of RSV vaccination for
mothers.”
Reference: “Bivalent prefusion F vaccination in pregnancy and respiratory syncytial virus hospitalization in infants in the UK: results of a multicenter, test-negative, case-control study” by Thomas C Williams, Robin Marlow, Steve Cunningham, et al., 18 July 2025, The Lancet Child & Adolescent Health.