Babies born via cesarean section may not mount as strong an immune response after some childhood vaccines compared to babies delivered vaginally, researchers suggest.
Antibody levels can be checked in blood or saliva, and babies born vaginally had higher levels of antibodies in their saliva to pneumonia shots at one year and meningococcal shots at 18 months, a new study showed.
But the study authors are quick to caution that their findings are not a reason to skip recommended childhood vaccinations.
"Vaccines are one of the best ways that you can protect your child against disease," said study author Debby Bogaert, a clinical fellow and honorary consultant in pediatric infectious diseases at the University of Edinburgh in Scotland. "Although we observed differences in how the two different groups of babies responded to the vaccines, there was still enough of an immune response in both groups to provide protection against infection."
The findings also can't be inferred to say whether babies born via C-section are more likely to develop other infections such as COVID-19, flu or respiratory syncytial virus (RSV), all of which are circulating now.
"Our research only focused on vaccines that are currently given in early childhood that protect against certain lung infections and meningitis," Bogaert said.
The study took place in the Netherlands, where vaccine schedules and recommendations differ from the United States. The U.S. Centers for Disease Control and Prevention recommends infants receive four doses of the pneumonia shot at 2, 4, 6 and 12-15 months. The meningococcal vaccine is not routinely recommended for infants in the U.S.
In addition to higher antibody levels against pneumonia and meningitis in saliva, infants born via vaginal delivery showed changes in their populations of good and bad gut bacteria that reflected the higher antibody responses to the two vaccines.
The study was published Nov. 15 in Nature Communications.
The findings add weight to other studies suggesting that the route of delivery can affect a baby's vaccine response, said Dr. Paul Krogstad, a professor of pediatrics and infectious diseases at UCLA Health in Los Angeles.
"The antibodies made from these two vaccines were highest in breast-fed and vaginally delivered infants," said Krogstad, who reviewed the findings.
"More women have the opportunity to choose to breastfeed versus bottle-feed, but the mode of delivery is largely driven by what is safest for mother and infant," he said.
Importantly, the new study can't say that babies born via C-section will get more infections or have more severe bouts of vaccine-preventable illnesses.
"It says the immune system is not as well prepared to produce antibodies that we can measure in the lab," Krogstad said.
More information is needed to draw any firm conclusions about how the new findings affect a baby's health and well-being.
Visit the U.S. Centers for Disease Control and Prevention to view the recommended infant vaccination schedule in the United States.
SOURCES: Debby Bogaert, PhD, senior clinical fellow and honorary consultant, pediatric infectious diseases, University of Edinburgh, Scotland; Paul Krogstad, MD, professor, pediatrics and infectious diseases, UCLA Health, Los Angeles; Nature Communications, Nov. 15, 2022