Study Shows That Breast Milk of Those Vaccinated Against COVID-19 Protects Infants


Antibodies help neutralize the virus, though the levels decrease at the 6-month mark, data indicate.

Breast milk from individuals who are vaccinated against COVID-19 provides protection to infants who are too young to be vaccinated, according to the results of a study published in Journal of Perinatology.

The results of a 2021 study from the University of Florida showed that the breast milk of vaccinated individuals contained antibodies against SARS-CoV-2, and in the new study, investigators analyzed the stool of infants that consumed the breast milk.

They found that the infants also had SARS-CoV-2 antibodies.

“Our first study showed there were SARS-CoV-2 antibodies in the breast milk, but we couldn’t say if those antibodies were getting through the babies’ gastrointestinal tract and possibly providing protection there,” Joseph Larkin III, an associate professor in the department of microbiology and cell science at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), said in a statement.

Investigators used neuralization assay to show that the antibodies found in the infants’ stool provided protection against COVID-19.

The assay isolated antibodies from the stool and added them to a special line of cells with receptors similar to ones the SARS-CoV-2 virus uses to enter the cell.

Investigators introduced a fluorescent pseudovirus of SARS-CoV-2, which is safer to use in a laboratory and lights up a cell when it binds to it.

“We saw that when the antibodies were present, there were fewer fluorescent cells compared to our controls where no antibodies were present,” Lauren Stafford a doctoral student at the UF/IFAS College of Agricultural and Life Sciences, said in the statement.

Additionally, investigators noted that even though COVID-19 is thought to mainly affect the lungs, it can also invade the gut, which is why finding the antibodies there is so significant.

Investigators also measured and evaluated the antibodies found in the mothers’ blood plasma and breast milk soon after vaccination, as well as 6 months later. They found that the antibodies in the milk and plasma were better able to neutralize the virus.

However, investigators also found that the antibody levels decreased at the 6-month mark, which they found was consistent with other vaccine studies.

Results of the first and second studies show a more complete picture of how vaccinating against COVID-19 during pregnancy and breastfeeding could protect both the child and parent, they said.

“In our research, we’re following the journey of the antibodies, from the time they are produced in mom after vaccination and now through the baby’s digestive system. The next question is whether those babies are less likely to get COVID-19,” Josef Neu, MD, a professor in the department of pediatrics and division of neonatology at UF College of Medicine, said in the statement.

Investigators called for larger studies to determine if the infants are less likely to get COVID-19. This study included 25 infants and 37 mothers, which they said was a relatively small number.

Children aged under 6 months cannot receive the vaccine, so this could be a way to provide immunity.


Scientists find more evidence that breast milk of those vaccinated against COVID-19 may protect infants. EurekAlert. News release. January 12, 2023. Accessed January 17, 2023.

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