COVID-19 antibodies persist in breast milk for months after mother is vaccinated

Breastfeeding mothers who receive a COVID-19 vaccine can pass protective antibodies to their babies through breast milk for at least 80 days after vaccination, suggests new research from the Washington University School of Medicine in St. Louis.

Our study showed a huge increase in antibodies to the COVID-19 virus in breast milk from two weeks after the first vaccine, and this response was maintained for the duration of our study, which lasted almost three months. . Antibody levels were still high at the end of our study, so protection will likely extend even longer. “

Jeannie Kelly, MD, lead author, assistant professor of obstetrics and gynecology, Washington University School of Medicine in St. Louis

Based on the small study, involving five mothers who provided samples of frozen breast milk after receiving the two-dose Pfizer-BioNTech coronavirus vaccine, the research provides some of the first peer-reviewed evidence that breastfeeding confers a long-lasting immune response to breastfeeding. infants and toddlers of vaccinated mothers.

“There is so much misinformation about vaccines right now – some really scary and misleading social media posts that are designed to scare off moms – so we felt we had to look at the science,” Kelly said. “We know that these types of antibodies cover the baby’s mouth and throat and protect against disease when a baby drinks breast milk. So getting the vaccine while breastfeeding not only protects the mom, but could also protect the mother. the baby, too, and for months. “

Published March 30 in the American Journal of Obstetrics and Gynecology, the study tracked COVID-19 antibody levels in breast milk from a baseline before mothers’ first vaccinations and on a weekly basis. for 80 days after these initial vaccinations.

While other recent research has shown that COVID-19 vaccines generate antibodies that are passed to infants through breast milk, it is believed to be the first study to track specific levels of these antibodies in the breast. breast milk over an extended period of time.

The babies of the women included in the study were between one month and 24 months old. To assess the immune response in breast milk, the researchers monitored the levels of immunoglobulins IgA and IgG, which are antibodies made by the immune system to fight infections in babies.

The results confirm that breast milk contains high levels of IgA and IgG antibodies immediately after the first dose of vaccination, with both antibodies reaching immuno-significant levels within 14 to 20 days of the first vaccination in all participants.

“Our study is limited by a small number of participants, but the results provide encouraging news about the potential immune benefit for breastfed infants after vaccination,” said lead study author Misty Good, MD, assistant professor of pediatrics, also in Washington. University. “Our article is the first to show that COVID-19 antibodies persist in breast milk for months after the mother is vaccinated.”

The results from the University of Washington are similar to previous studies on maternal vaccination, which showed high levels of antibodies in breast milk for up to six months after vaccination against influenza and pertussis.

While further studies on maternal COVID-19 vaccination are needed to characterize the duration of antibody production in breast milk and its effect on infant infection rates, recent research continues to confirm that the COVID-19 vaccine offers real benefits for the protection of mother and child.

“We know that COVID-19 infection is more serious during pregnancy and the main benefit of vaccination is to provide protection to mothers before they get really sick, which can also be dangerous for their fetus” said Kelly. “There are now nearly 70,000 pregnant women vaccinated against COVID 19 without any evidence of harm.”

“We are now seeing a cascade of new data indicating that maternal vaccines will also help protect babies – both by transferring antibodies through the placenta during pregnancy and through breast milk while breastfeeding. “Kelly said. “This is information we didn’t have a few months ago and it really helps us better counsel our patients who are considering getting vaccinated. I tell my pregnant and breastfeeding moms that I strongly recommend that they get vaccinated as soon as possible. “


Washington University School of Medicine in St. Louis

Journal reference:

Kelly, JC, et al. (2021) Anti-SARS-CoV-2 antibodies induced in breast milk after Pfizer-BioNTech / BNT162b2 vaccination. American Journal of Obstetrics and Gynecology.