Breastfeeding taskforce

Nursing mothers pass COVID antibodies to infants

AMHERST – Researchers at the University of Massachusetts Amherst have found further evidence that women vaccinated against COVID-19 pass anti-coronavirus antibodies to their children through their breast milk.

The study was published in November in the American College of Obstetricians and Gynecologists’ peer-reviewed journal, Obstetrics & Gynecology, and it found the first evidence of antibodies against SARS-CoV-2, the virus that causes COVID-19, in stool samples from infants breastfed by vaccinated mothers. The study’s lead authors were Ph.D. candidate Vignesh Narayanaswamy and Kathleen Arcaro, a professor of environmental toxicology in the Department of Veterinary and Animal Sciences who directs the university’s Breast Milk Research Laboratory.

“It’s really important because women want to know if their babies have these antibodies, and our study shows that the antibodies are transferred via breast milk,” Narayanaswamy said.

Speaking to the Gazette on Friday, Narayanaswamy said the study had important implications for parents and their children.

“Especially in the context of COVID and vaccinated people, it’s really important for mothers to continue breastfeeding,” Narayanaswamy said, adding that many studies have shown the benefits of breast milk for the immune system of infants.

The paper was the latest to come out of Arcaro’s lab analyzing whether those who are vaccinated and breastfeeding pass on coronavirus immunity to their children. A year ago, Narayanaswamy and Arcaro published a study showing anti-SARS-CoV-2 antibodies in the colostrum, or “first milk,” of women who tested positive for COVID-19.

In their latest research, Narayanaswamy said that the 30 women who participated in the study received one of two mRNA vaccines, from Moderna and Pfizer, after giving birth. Participants gave breast milk samples before vaccination, several weeks after the first dose, and three weeks after the second dose.

The researchers also took blood samples from the mothers and stool samples from the infants. Antibodies were detected in about one-third of stool samples from infants.

In a university press release announcing the research, Arcaro noted that antibody levels detected in stool samples correlated with the degree to which the mother experienced side effects from the vaccine.

“Women who felt sick from the vaccine were associated with higher amounts of antibodies in infant stool,” Arcaro said. “So you may have felt bad, but it was a plus for your baby.”

Narayanaswamy said the children in the study ranged in age from 1.5 months to 23 months. He also said the study found antibodies in the breast milk of 87% of vaccinated participants. The answer to the question of why not all women had an immune response will need further study, he said.

“We just don’t know,” Narayanaswamy said.

The research paper said the “major limitation” of the study was the small sample size, “which did not allow us to explore the reasons for the different immune responses in women.”

The research is likely good news for breastfeeding families and expectant parents.

“It’s all the more reason to encourage mothers to breastfeed their babies,” said pediatrician Jonathan Schwab, medical director of Northampton Area Pediatrics.

Schwab said previous research had shown that breastfed infants received other antibodies through breast milk, either because their mother had been infected or had received a vaccine. The UMass Amherst study, he said, proves what many had suspected but did not yet know as fact about COVID-19 vaccines.

“We always guessed and assumed it would” because of the analogy to other infections and vaccines, Schwab said. “It proves things that we thought were the case but didn’t know.”

The research team included UMass d’Arcaro colleagues Dominique Alfandari, Brian Pentecost, and Sallie Schneider; Dr. Corina Schoen, assistant professor of obstetrics and gynecology at UMass Chan Medical School-Baystate; and UMass Amherst undergraduate student Ryan Baker

Dusty Christensen can be contacted at [email protected]