Breast milk from individuals vaccinated against COVID-19 provides protection to infants too young to be vaccinated, according to 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 to SARS-CoV-2, and in the new study, researchers analyzed the stools of infants who consumed the breast milk.
They found that the babies also had SARS-CoV-2 antibodies.
“Our initial study showed that there were SARS-CoV-2 antibodies in breast milk, but we couldn’t tell if those antibodies passed through the babies’ gastrointestinal tract and might have provided protection there,” said 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), in a statement.
Researchers used a neuralization test to show that the antibodies found in the babies’ stools offered protection against COVID-19.
The test isolated antibodies from stool and added them to a special set of cells with receptors similar to those used by the SARS-CoV-2 virus to enter the cell.
Researchers introduced a fluorescent pseudovirus of SARS-CoV-2, which is safer to use in a lab and illuminates 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 in the UF/IFAS College of Agricultural and Life Sciences, said in the statement.
In addition, researchers noted that while COVID-19 is believed to primarily affect the lungs, it can also enter the gut, which is why finding the antibodies there is so important.
Researchers also measured and evaluated the antibodies found in the mother’s blood plasma and breast milk shortly after vaccination, and also six months later. They discovered that the antibodies in the milk and plasma were better able to neutralize the virus.
However, researchers also found that antibody levels decreased after 6 months, which they said was consistent with other vaccine studies.
The results of the first and second studies show a more complete picture of how vaccination against COVID-19 during pregnancy and breastfeeding can protect both the child and the parent, they said.
“In our research, we follow the journey of the antibodies, from when they are produced in the mother 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 department of neonatology at UF College of Medicine, said in the statement.
Researchers called for larger studies to determine if the babies are less likely to get COVID-19. This study included 25 babies and 37 mothers, which they said was a relatively small number.
Children younger than 6 months cannot receive the vaccine, so this may be one way to provide immunity.
Scientists are finding more evidence that breast milk from those vaccinated against COVID-19 can protect babies. EurekAlert. Press release. January 12, 2023. Accessed January 17, 2023. https://www.eurekalert.org/news-releases/976087