UMass study: Breastfeeding moms pass COVID antibodies to infants

  • The University of Massachusetts Amherst campus Courtesy photo

  • University of Massachusetts Amherst Ph.D. candidate Vignesh Narayanaswamy was one of the lead authors of the study, along with UMass Professor Kathleen Arcaro. —UMASS AMHERST

Staff Writer
Monday, January 17, 2022

AMHERST — University of Massachusetts Amherst researchers have found further evidence that women vaccinated against COVID-19 pass coronavirus antibodies to their children through their breast milk.

The study was published in November in the peer-reviewed journal of the American College of Obstetricians and Gynecologists, Obstetrics & Gynecology, and it found the first evidence of antibodies against SARS-CoV-2, the virus that causes COVID-19, in stool samples of infants who had breastfed from 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 leads the university’s breast milk research lab.

“This is really important because women want to know whether their babies have these antibodies, and our study shows that antibodies are being transferred via breast milk,” Narayanaswamy said.

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

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

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

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

The researchers also collected blood samples from the mothers and stool samples from the infants. Antibodies were detected in around a third of the infants’ stool samples.

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

“Women who did feel sick from the vaccine was associated with greater antibodies in the infant stool,” Arcaro said. “So you might have felt badly, but that was a benefit for your infant.”

Narayanaswamy said that the children in the study ranged from 1.5 months old to 23 months old. He also said that the study found some antibodies in the breast milk of 87% of the vaccinated participants. Answering why not all of the women had an immune response will have to be the subject of further study, he said.

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

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

The research is likely welcome news to breastfeeding families and expectant parents.

“This is yet one more reason that we encourage mothers to breastfeed their babies,” said pediatrician Jonathan Schwab, the medical director of Northampton Area Pediatrics.

Schwab said previous research has shown that breastfeeding infants get other antibodies through breast milk, either because their mother had been infected or had a vaccine. The UMass Amherst study, he said, proves what many had suspected but didn’t know yet as a fact about the COVID-19 vaccines.

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