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COVID-19 Vaccine Likely Beneficial For Breastfed Babies, But Questions Remain

Dr. Kathryn Pade
Samples of breastmilk from Dr. Kathryn Pade, who received the COVID-19 vaccine and then provided milk to UC San Diego for research, appear in this undated photo.

This is part two of a two-part series. Read part one here.

Jennifer Elwell, a nurse at UC San Diego, has been breastfeeding since her eight-month-old son was born. She also recently completed both doses of the COVID-19 vaccine.

“Right after I got the first vaccine, I came home and fed him, since that’s what I always do, but then I completely panicked, thinking, ‘what have I done, that was a total mistake,’” she said.

COVID-19 Vaccine Likely Beneficial For Breastfed Babies, But Questions Remain
Listen to this story by Claire Trageser.

Elwell knows it was an irrational response — she’d studied research about breastfeeding and the COVID-19 vaccines and knew doctors and medical experts recommend women who receive the vaccines continue breastfeeding. In fact, the conventional wisdom among medical professionals is that women who get the vaccine may pass on protective antibodies to the baby through their milk.

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Yet, Elwell’s uncertainty is understandable given the fact that no clinical trials of COVID-19 vaccines were done on pregnant or breastfeeding women. Excluding women who are new mothers or expecting has traditionally been standard practice for clinical trials of any new drug or vaccine, but some doctors and medical experts now say this was a mistake when it comes to the coronavirus.

Dr. Christina Chambers
A researcher at UC San Diego takes samples of breastmilk from a woman who received the COVID-19 vaccine, Jan. 29, 2021.

“Hindsight is 2020, though we shouldn’t use 2020 anymore as an example because it was a horrible year clearly,” said Dr. Lars Bode, who runs the UC San Diego Mother-Milk-Infant Center of Research Excellence. “The notion was to originally protect women when they’re in this special space of being either pregnant or breastfeeding, but really what we should do is protect women and their babies by including them in the research and then have data on whether it’s safe or not.”

Now Bode is working on just that with Dr. Christina Chambers who for the past six years has led the UC San Diego nationwide biorepository for breastmilk called Mommy’s Milk that studies the effects of all kinds of things on mother’s milk.

“Back in March, when the pandemic started, we also enrolled women who had infections, tested positive for COVID while breastfeeding, because back then there was a lot of concern that milk could transmit to COVID to a baby,” said Chambers.

Using that early data, they were able to show that the COVID-19-positive women likely did not transfer virus to their babies through breastmilk, but did transfer antibodies that could protect the baby from infection.

“That changed the (World Health Organization) recommendation to be that COVID-postive women should wear a mask and continue breastfeeding and led to reassuring messages about breastfeeding, that actually the worst thing to do is stop breastfeeding, because then you end the protection,” Chambers said.

Now, Chambers and other UC San Diego researchers are extending their studies to women who’ve received COVID-19 vaccines. So far, 1,250 women from across the country who’ve have received a vaccine are shipping Mommy’s Milk bags of pumped breastmilk — one bag from before the vaccine and seven more over two months after getting the first dose.

“We’re looking at, can a mother provide protection to her baby,” Chambers said. “We’ll also look at other things about the milk, whether there’s any change in fat, carbohydrate or protein content of milk, difference in milk supply, and indications if the baby has any unusual signs or symptoms.”

Expectant Mothers Aren't Getting Clear Guidance About COVID-19 Vaccines

Answers to questions regarding the vaccines’ impact on the health of babies will take the most time, but the researchers are cautiously optimistic.

“From everything we’ve seen so far with other diseases outside this pandemic, we’re fairly confident we will find antibodies,” Bode said.

He also expects to find that the vaccines do not put anything in breastmilk that is harmful to babies. Breastfeeding women take other vaccines that don’t transfer viruses through breastmilk, and the COVID-19 vaccines are made with a messenger RNA, not a live virus like most other vaccines. Messenger RNA carries instructions to tell our bodies’ cells how to make a protein that triggers an immune response, thereby teaching our bodies to fight off COVID-19 inside our bodies.

“I do not have any concerns that the messenger RNA gets anywhere near the milk, but if it gets into the milk, it’s a very unstable molecule so it’s very unlikely it would have any impact on the baby,” Bode said.

All of these theories were compelling to Dr. Kathryn Pade, an ER doctor at Rady Children’s Hospital and mother of a six-month-old. She took the vaccine, continues to breastfeed and is one of the study participants.

Dr. Kathryn Pade
The six-month-old daughter of Dr. Kathryn Pade wears a "My milk was spiked" onesie because her mother received the COVID-19 vaccine in this undated photo.

As any breastfeeding mother knows, it can feel painful to give up any pumped milk, but Pade said it was worth it in this case, Pade said it was worth it.

“They took one to two ounces with each sample, so in total it’s 15 to 20 ounces,” she said. “That’s not even a day’s worth of feed, and it was worth it for science.”

That science is what other moms like Carly Keatts are waiting for. She is breastfeeding her son and is generally very pro vaccine, but says it’s hard to make a decision without data.

“There’s no actual data yet saying anything from the vaccine doesn’t pass through, and if it does, maybe it’s good or bad, but there’s nothing in the data yet saying it’s 100% good for me and the baby,” Keatts said.

While other women might say they will not get the vaccine and keep themselves safe while breastfeeding, Keatts knows from experience that isn’t always possible.

“I thought I was doing everything I could to prevent it, but sadly I did get COVID,” she said. “I was nursing at the time, and the doctors advised me to wear a mask and continue nursing because antibodies will be passed along. But I’m wondering, because this isn’t like other shots, do those antibodies still pass over.”

Keatts may have an answer by the time it’s her turn for a vaccine, as results from the first 500 women from the UC San Diego study are expected in a few months.