Birth by C-section increases odds of measles vaccine failure

Researchers from the University of Cambridge and Fudan University have found that a single dose of the measles vaccine is up to 2.6 times more likely to be completely ineffective in children born by caesarean section, compared to those born naturally. 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.

Measles 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. At least 95% of the population needs to be fully vaccinated to keep measles under control, so even low vaccine failure rates can increase the risk of an outbreak.

Meanwhile, 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, while 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, and so miss out on the immune system boost that comes with it.

“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,” noted Cambridge’s Professor Henrik Salje, joint senior author of the new study.

The researchers analysed data from previous studies of over 1500 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. Their results were published in the journal Nature Microbiology.

While many of the children born by C-section did mount an immune response following their first vaccination, 12% had no immune response, compared to 5% of children born by vaginal delivery. A second measles jab was found to induce robust immunity against measles in C-section children; indeed, everyone needs two doses of the vaccine in order for the body to mount a long-lasting immune response.

“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,” Salje said.

“Vaccine hesitancy is really problematic, and measles is top of the list of diseases we’re worried about because it’s so infectious.

“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.”

Image credit: iStock.com/Natalya Maisheva

This is a modified version of a news item published by the University of Cambridge under CC BY-NC-SA 4.0. This version is similarly licensed under CC BY-NC-SA 4.0.

Originally published here.