Babies in intensive care with RSV halved in England in the first full winter of vaccinating in pregnancy, 63 against 132 the year before

Respiratory syncytial virus, or RSV, infects around 9 in 10 children in their first two years of life, and for most of them it passes as a cold. For a few it does not. The virus can swell the smallest airways in a baby's lungs, an illness called bronchiolitis, and every winter some of the youngest need breathing support in hospital. Last winter, across the 20 NHS trusts in England that count them, 63 babies under six months went into intensive care or high dependency care, the step below it, with a confirmed RSV infection. The winter before, the same 20 trusts reported 132. The virus had not changed. What changed is that from September 2024 the NHS began offering every pregnant woman a vaccine from 28 weeks, a maternal immunisation, meaning the mother is vaccinated so that the antibodies she makes cross the placenta and protect her baby from the day it is born. Winter 2025 to 2026 was the first full season in which most newborns in England arrived already carrying that protection.

How we know

The count comes from the UK Health Security Agency's annual RSV surveillance report, published on 13 August 2026. The infant figures are drawn from SARI Watch, a system built on sentinel surveillance, meaning a small network of hospitals reports in detail rather than every hospital reporting a little. Twenty acute NHS trusts took part in both winters, and that is what makes the comparison a fair one: the same hospitals, counting the same way, either side of the programme. Across all ages those trusts recorded 196 intensive care or high dependency admissions for RSV between early September 2025 and early April 2026, against 277 in the same weeks a year earlier. Children under five accounted for 132 of the 196, down from 214. The babies under six months, the group the maternal immunisation programme is meant to reach, accounted for 63 of those, down from 132.

Two other indicators move the same way. Emergency department attendances for bronchiolitis or bronchitis among children under one totalled 18,137 across the winter, down from 22,585 the year before and 24,442 in 2022 to 2023. And the size of the fall matches what earlier studies had predicted: a population study in Scotland measured the vaccine effectiveness of the maternal jab, meaning how well it performed once rolled out to a whole population rather than inside the trial that licensed it, at 82 percent against RSV hospital admission in babies aged 90 days or younger during the programme's first season. The separate NHS programme for adults from 75 shows the same shape in its own data. RSV hospital admission rates among those aged 75 to 80 when it began ran 43 percent below what the modelling expected without it, and a pooled estimate across the four UK nations put vaccine effectiveness against RSV hospital admission at 75 percent in adults aged 75 to 79. One discrepancy is worth naming: UKHSA's news release gives last winter's infant figure as 131, where the report itself says 132 and its own percentages are consistent with 132, so 132 is the figure used here.

Why it matters

The point of vaccinating in pregnancy is timing. UKHSA's immunisation handbook is blunt about the alternative: there are no approved RSV vaccines for infants, and such an approach is unlikely to protect during the most vulnerable first months of life, because a newborn's immune system is too immature to respond well. So the protection has to arrive from outside, and a maternal immunisation is one of only two ways to deliver it, the other being an antibody injected into the baby directly. UKHSA advises the vaccine in week 28 or soon after, so that most babies born early are covered too, and says it still helps given as little as ten days before labour begins. What last winter adds is that the arithmetic holds outside a trial, across a whole health service, in a season the report describes as starting and peaking later than usual. The limit now is not the science. In the 12 months to February 2026, 61.7 percent of women giving birth in England had been vaccinated, which leaves close to four pregnancies in ten without it, and UKHSA published the result with a warning attached: many thousands of babies remain at risk. Whether those four in ten are reached is a question about maternity services and the conversations held in them, not about whether the vaccine works.