Vaccinated mothers who breastfeed could pass COVID-19 antibodies to infants, study finds

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Researchers say they still need to confirm if protection is passed between mothers and children

A new study conducted by researchers from the University of Florida explored how the COVID-19 vaccine may protect breastfeeding mothers and their children. 

According to their findings, samples of breast milk from women who had received the COVID-19 vaccine contained antibodies that protect against the virus. The team says this may be beneficial in keeping infants free of infection. 

“Our findings show that vaccination results in a significant increase in antibodies against SARS-CoV-2 -- the virus that causes COVID-19 -- in breast milk, suggesting that vaccinated mothers can pass on the immunity to their babies, something we are working to confirm in our ongoing research,” said researcher Joseph Larkin III, Ph.D. 

Increasing the number of antibodies

The researchers had 21 breastfeeding women who had never been infected with COVID-19 participate in the study. The researchers tested samples of the women’s breast milk and blood prior to getting vaccinated and after each dose of the vaccine to get an accurate antibody reading. 

Ultimately, the results showed that the women’s breast milk contained significant amounts of COVID-19 antibodies. According to the team, there was about “a hundred-fold increase” in antibody levels between pre- and post-vaccination. 

“These levels are also higher than those observed after natural infection with the virus,” said researcher Dr. Vivian Valcarce. 

Protection for children

Despite these positive results, the researchers are left with further questions for future studies. They say it remains unclear if the antibodies detected in the women’s breast milk will serve as a protective barrier for infants. 

“We would like to know if infants who consume breast milk containing these antibodies develop their own protection against COVID-19,” Dr. Larkin said. “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.” 

While more work is likely to be done to determine the efficacy of this form of protection for infants, these findings highlight one of the ways that the COVID-19 vaccine can be beneficial to breastfeeding women. 

“Think of breast milk as a toolbox full of all the different tools that help prepare the infant for life,” said researcher Dr. Josef Neu. “Vaccination adds another tool to the toolbox, one that has the potential to be especially good at preventing COVID-19 illness. The results of our study strongly suggest that vaccines can help protect both mom and baby, another compelling reason for pregnant or lactating women to get vaccinated.” 

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