The measles vaccine does not work as well in children born by caesarean, a study by the University of Cambridge has revealed.
Experts found that the jab was more than twice as likely to fail in children who had been born by caesarean section rather by a vaginal delivery. The analysis revealed that 12 per cent of children born by caesarean had no immune response after one dose of the measles vaccine compared to five per cent of children who were born naturally.
The researchers said it highlighted the need for children to have both doses in order to be protected against the disease. It comes as the UK is experiencing its biggest outbreak of measles in a decade amid falling vaccination rates.
The latest figures show just 89.1 per cent of children in the UK have had the first dose of their measles, mumps and rubella (MMR) vaccine by the age of two, while even fewer have had two doses – just 85 per cent by age five. The target in order to develop herd immunity and prevent outbreaks is 95 per cent.
The team from Cambridge and the Fudan University in China studied 1,505 children from Hunan, China, and took blood samples every few weeks from birth to age 12. They analysed how immunity to measles changed over time including after vaccination.
They found that “c-section births were linked with 2.56 increased odds of primary vaccine failure”, compared to babies born naturally, but this was later rectified by a second dose of the jab.
Second jab vital
The findings build on evidence that children born via caesarean have weaker immunity at the start of life because they are not exposed to the variety of microbes that those born vaginally are.
Professor Henrik Salje, from the University of Cambridge and a senior author of the study, said: “With a c-section birth, children aren’t exposed to the mother’s microbiome in the same way as with a vaginal birth. We think this means they take longer to catch up in developing their gut microbiome, and with it, the ability of the immune system to be primed by vaccines against diseases including measles.
“We know that a lot of children don’t end up having their second measles jab, which is dangerous for them as individuals and for the wider population,” he said. “Infants born by c-section are the ones we really want to be following up to make sure they get their second measles jab, because their first jab is much more likely to fail.”
Prof Salje added that “measles is top of the list of diseases we’re worried about because it’s so infectious”.
Dr Mary Ramsay, director for immunisation at the UK Health Security Agency (UKHSA), said: “The Joint Committee on Vaccination and Immunisation regularly reviews all new and available evidence… Our evidence suggests that two doses of the vaccine are highly protective, and the majority of cases we are seeing are in unvaccinated children.”
In the UK, the first dose of the MMR jab is usually given on the NHS at the age of one. A second dose is given between the three-years-and-four-months and five-years-old.
Adam Finn, professor of paediatrics at the University of Bristol, said the new data did not prove a cause. But he added: “This evidence adds to previous evidence relating to other vaccines which has suggested that babies born by vaginal delivery and/or who are breastfed make stronger or more reliable immune responses.”
He said the new research “raises important questions that need to be researched further, because many children are born by caesarean delivery these days and the rates continue to rise”. Last year 39 per cent of all babies were born by caesarean, including 55 per cent of women over 40, compared to 34 per cent in their 20s. The latest monthly data for January this year shows 19 per cent of births were planned c-sections, and 24 per cent were emergency.
The study was published in the journal Nature Microbiology.
Source Agencies
