COVID-19 antibodies survive in breast milk for months after vaccination of the mother

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

Our study showed a huge increase in antibodies to the COVID-19 virus in breast milk starting two weeks after the first burst, and this response was retained during our study, which lasted nearly three months. At the end of our study, antibody levels were still high, so protection is likely to extend even longer. “

Jeannie Kelly, Ph.D. Med., First Author, Assistant Professor of Obstetrics and Gynecology, University of Washington School of Medicine, St. Louis

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

“There’s so much misinformation about vaccines right now – really scary, deceptive social media posts created to scare moms – so we felt like we had to look at science,” Kelly said. “We know that these types of antibodies cover the baby’s mouth and throat and protect against disease when the baby drinks breast milk. So vaccination during breastfeeding not only protects the mother, but could also protect the baby, for months.”

Published March 30 in the American Journal of Obstetrics and Gynecology, the study monitored the level of COVID-19 antibodies in breast milk from baseline before the first vaccinations of mothers and weekly for 80 days after those initial vaccinations.

Although other recent studies have shown that COVID-19 vaccines generate antibodies that are transmitted through breast milk, this is considered to be the first study to monitor specific levels of these antibodies in breast milk over a long period of time.

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

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

“Our study is limited by the small number of participants, but the findings provide encouraging news about the potential immune benefits for infants after vaccination,” said senior study author Misty Good, an assistant professor of pediatrics, also from Washington University. “Our work is the first to show that antibodies to COVID-19 survive in breast milk for months after maternal vaccination.”

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

Although further maternal vaccination studies with COVID-19 are needed to characterize the length of antibody production in breast milk and the effect on neonatal infection rates, recent research continues to confirm that COVID-19 offers real benefits for maternal and child protection.

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

“We are now seeing a cascade of new data suggesting that maternal vaccines will also help protect babies – both by transmitting antibodies through the placenta during pregnancy and through breast milk during lactation,” Kelly said. “These are data we didn’t have a few months ago and they really help us better advise our patients who are considering a vaccine. I tell pregnant and breastfeeding women that I strongly recommend that they get vaccinated as soon as possible.”


Washington University School of Medicine, St. Louis. Louis

Journal reference:

Kelly, JC, and others. (2021) Antibodies to SARS-CoV-2 induced in breast milk after vaccination with Pfizer-BioNTech / BNT162b2. American Journal of Obstetrics and Gynecology.