Women who received two doses of the COVID-19 vaccine pass antibodies against the virus to their infants through breastfeeding, a new study from UMass Amherst shows.
“Our study shows that antibodies are being transferred via breast milk. Providing this compelling evidence is motivation for women to continue breastfeeding after they receive the vaccine,” said Vignesh Narayanaswamy, a Ph.D. candidate who was the lead author of the study.
Researchers recruited 30 women from across the country who were breastfeeding and planned to receive mRNA doses in 2021, between January and April. Scientists took samples of the mothers’ breastmilk and blood before and after each dose of either Pfizer or Moderna. The results indicated antibodies in the breast milk that were found to neutralize the protein spike of COVID-19, as well as four variants.
Narayanaswamy said those results were not surprising, but what they found next was interesting. In addition to the mothers’ samples, researchers studied the babies’ stool samples. Anyone with a newborn knows those samples can be readily accessed.
“We were able to detect antibodies in those subsets of stool samples,” he told the Herald, indicating the babies may have the antibodies in the mucus of their GI tract, potentially offering protection against coronavirus.
“These are infants who never had COVID, and certainly didn’t have the vaccine, so it’s sort of like a passed immunity,” Narayanaswamy said.
Researchers found antibodies in samples from infants ranging in age from just under two months old to nearly two years old.
Antibodies were detected in about one-third of all samples in the study, and even more interestingly, the levels of antibodies appeared to correlate with whether the mother felt side effects from the vaccine.
“Women who did feel sick from the vaccine was associated with greater antibodies in the infant stool,” said UMass Amherst Ph.D. candidate Kathleen Acaro in a statement. “So you might have felt badly, but that was a benefit for your infant.”
Narayanaswamy said the study just passed its one-year mark and researchers intend to reach back out to the moms enrolled to see whether they continue to breastfeed the same infant from the study last year and the effects of booster doses on antibody levels in infants.