HQ Team
May 17, 2024: A measles vaccine given to a child born by caesarean section is likely to be 2.6 times completely ineffective than a normal delivery, a study by the University of Cambridge found.
A potential reason for this effect is linked to the development of the infant’s gut microbiome — the vast collection of microbes that naturally live inside the gut. Other studies have shown that vaginal birth transfers a greater variety of microbes from the mother to the baby, which can boost the immune system.
Failure of the vaccine means that the child’s immune system does not produce antibodies to fight against measles infection, so they remain susceptible to the disease.
A second measles jab was found to induce robust immunity against measles in C-section children, according to a statement from the university.
Outbreak risk
Measles is a highly infectious disease, and even low vaccine failure rates can significantly increase the risk of an outbreak. It is one of the world’s most contagious diseases, spread by coughs and sneezes. It starts with cold-like symptoms and a rash and can lead to serious complications including blindness, seizures, and death.
The researchers used data from previous studies of more than 1,500 children in Hunan, China, which included blood samples taken every few weeks from birth to the age of 12. This allowed them to see how levels of measles antibodies in the blood change over the first few years of life, including following vaccination.
They found that 12% of children born through caesarean section had no immune response to their first measles vaccination, as compared to 5% of children born by vaginal delivery. This meant that many of the children born by C-section still mounted an immune response following their first vaccination.
“We’ve discovered that the way we’re born – either by C-section or natural birth – has long-term consequences on our immunity to diseases as we grow up,” said Professor Henrik Salje in the University of Cambridge’s Department of Genetics, joint senior author of the report.
Second jab
“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.
“Infants born by C-section are the ones we want to be following up to make sure they get their second measles jab because their first jab is much more likely to fail.”
At least 95% of the population needs to be fully vaccinated to keep measles under control but the UK is well below this, despite the Measles, Mumps and Rubella vaccine being available through the NHS Routine Childhood Immunisation Programme.
An increasing number of women around the world are choosing to give birth by caesarean section. in the UK a third of all births are by C-section, in Brazil and Turkey over half of all children are born this way.
“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,” said Salje.
Vaccine hesitancy
Two doses of the measles jab are needed for the body to mount a long-lasting immune response and protect against measles. According to the World Health Organisation, in 2022 only 83% of the world’s children had received one dose of measles vaccine by their first birthday – the lowest since 2008.
“Vaccine hesitancy is problematic, and measles is top of the list of diseases we’re worried about because it’s so infectious,” Salje said.
Before the measles vaccine was introduced in 1963, there were major measles epidemics every few years causing an estimated 2.6 million deaths each year. The research was funded by the National Natural Science Foundation of China.
