Study: COVID-19 antibodies passed to infants through breastmilk

Jan. 7—Limited data is available about the risks and benefits associated with breastfeeding following a positive COVID-19 diagnosis.

Scientists at the University of Idaho, however, recently published a study which supports recommendations for lactating mothers to continue breastfeeding during and after illness.

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"It's a huge relief," Michelle McGuire, a professor at the university, said. "There's no other way to put it."

She helped lead the multidisciplinary research team in discovering breastmilk from women infected with COVID-19 provides natural protection to their infants against the virus. McGuire is a nutrition researcher focused on human milk.

Previous research from the scientists, funded by the Bill and Melinda Gates Foundation, found the milk of breastfeeding women with the illness to contain no traces of the virus.

"The next question was, 'Are there antibodies in breastmilk?' " McGuire said. "And lo and behold, they're there. The antibodies are there in relatively high amounts, they're long lasting and they neutralize or basically inactivate the virus."

More than 60 women participated in the expanded study by providing samples of milk for as long as two months after being diagnosed with COVID-19.

The results were published Dec. 23 in the journal Frontiers in Immunology. It includes work from researchers at UI, Washington State University, University of Rochester Medical Center, University of California, San Francisco, Brigham and Women's Hospital, University of Arkansas for Medical Sciences and Tulane University.

"It's another reminder that the human body is amazing," McGuire said. "Here we have moms producing antibodies to this pandemic virus that probably protects the baby in a big way. It's mother nature doing its thing."

Early in the COVID-19 pandemic, she said it was difficult to collect samples from women dealing with the illness and a newborn child. The few studies which did come out weren't reliable.

She said the group was the first in the country to look at the issue seriously.

Despite the logistical challenges, her team succeeded in retrieving breastmilk from infected women residing across more than 20 different states.

"It was an international crisis for months," McGuire said. "If a mom went to deliver a baby and she tested positive for COVID-19, she was separated from that baby as soon as it was delivered and oftentimes was not allowed to see that baby for two weeks. In many places in the world, there's no good alternative to breastfeeding."

The latest research was financially supported by both the Gates Foundation and the National Science Foundation.

McGuire, who's studied breastfeeding for decades, drew comparisons between the current pandemic and the HIV epidemic of the 1980s and 1990s.

"We found that HIV could in fact be transmitted via breastfeeding," she said. "In the end, breastfeeding still provided more benefits to babies than the risk of getting HIV but that took about a decade to figure out. The international recommendations for breastfeeding during that time were a mess."

Other viruses like Ebola and Zika have also been found to be passed from mother to infant through breastfeeding.

"It wasn't a crazy idea at all that babies could get COVID-19 from their moms via milk," McGuire said.

She added that the study was a massive team effort. Aside from McGuire, postdoctoral researcher Ryan Pace, senior research scientist Janet Williams, distinguished UI professor Mark McGuire and WSU professor Courtney Meehan made significant contributions to the research. Mark McGuire is Michelle McGuire's husband, and they often work together.

Antti Seppo from the University of Rochester Medical Center also helped lead the study.

Palermo can be reached at or on Twitter @apalermotweets.