Breast milk of mothers vaccinated against COVID-19 contains virus-fighting antibodies

GAINESVILLE, Fla. — Breast milk of mothers who have been vaccinated against COVID-19 contains virus-resistant antibodies. Mothers who have been double-vaccinated pass on 100 times more antibodies to their children than those who have not been jabbed, according to a new study.

Newborn babies have weaker immune systems, making it difficult for them to fend off infections and illnesses. They are also often too young to respond properly to certain types of vaccines, experts said. During this vulnerable period, babies rely heavily on their mother’s breast milk, which contains the necessary antibodies to a string of diseases. Now, researchers at the University of Florida say antibodies from COVID vaccines also pass from mother to child in breast milk. 

“Think of breast milk as a toolbox full of all the different tools that help prepare the infant for life. Vaccination adds another tool to the toolbox, one that has the potential to be especially good at preventing Covid-19 illness,” says co-author Dr. Josef Neu, a professor in the UF College of Medicine’s department of pediatrics, division of neonatology, in a statement.

The study was carried out between December 2020 and March 2021, when the Pfizer and Moderna vaccines first became available to healthcare workers. Researchers recruited 21 lactating healthcare workers who had never contracted COVID-19 before. Participants’ breast milk and blood were sampled three times, including before vaccination, after the first dose, and after the second.

“We saw a robust antibody response in blood and breast milk after the second dose — about a hundred-fold increase compared with levels before vaccination,” notes doctoral student and co-author Lauren Stafford. Antibody levels among vaccinated mothers were also higher than those recorded among people who had previously been infected with the virus. That mothers pass on the protective benefits of vaccinations to their children is nothing new.

“Typically, expectant mothers are vaccinated against whooping cough and flu because these can be serious illnesses for infants. Babies can also catch COVID-19, so routine vaccination of mothers against the virus could be something we see in the future,” adds co-author, Dr. Vivian Valcarce, a resident in the UF College of Medicine’s department of pediatrics, division of neonatology.

How exactly breast milk that contains COVID-19 antibodies protects babies remains a mystery and is now being explored.

“We would like to know if infants who consume breast milk containing these antibodies develop their own protection against COVID-19. In addition, we would also like to know more about the antibodies themselves, such as how long they are present in breast milk and how effective they are at neutralizing the virus,” explains Dr. Joseph Larkin III, senior author of the study, and an associate professor in the university’s department of microbiology and cell science.

Possible therapeutic applications of breast milk produced by vaccinated mothers are also being considered. “There is still so much we are learning about breast milk and all its benefits, and that’s what makes this research so fascinating, not just for us scientists but for non-scientists, too,” Stafford adds.

The study, funded by the Children’s Miracle Network, adds to the growing body of evidence that breast milk from vaccinated mothers contains COVID-resistant antibodies. “We are also excited to see many other simultaneous studies conducted around the world that also show antibodies in the breastmilk of vaccinated mothers. That means our study validates a growing body of evidence,” says Neu.

The findings are published in the journal Breastfeeding Medicine.

South West News Service writer Tom Campbell contributed to this report.