Pregnant women who recovered from COVID-19 or were vaccinated are likely to pass on antibodies to fetuses in their womb and to their babies through breastfeeding, experts and preliminary studies have suggested.
When the Shaare Zedek Medical Center in Jerusalem had to develop a protocol to care for infants born from infected mothers as the coronavirus crisis was just beginning, doctors did not have any doubt: it was important to do everything possible so that the babies would receive breast milk.
“We developed specific guidelines, including advising mothers to wear masks as they breastfed, but it was clear to everyone that a woman who got sick was probably going to develop antibodies against the disease and those could be passed on to the babies,” said Dr. Alona Bin-Nun, a neonatologist and director of the Neonatal Intensive Care Unit at Shaare Zedek.
While it is generally known that children can receive different types of antibodies through nursing, scientific literature on the specific topic of COVID-19 is still meager.
Researchers at the Providence Cancer Institute in Oregon recently analyzed milk samples from a group of six mothers, half of whom received the Moderna vaccine and the other half who received the Pfizer version.
The milk tested negative for antibodies before the mothers were vaccinated, and spiked afterward. Breast milk samples were collected pre-vaccination and at 11 additional time-points, with the last sample taken 14 days after the second vaccine dose. No adverse effects were discovered among the babies.
“We saw this spike [in antibodies] that started to climb at seven days after the first shot, and then it dips down,” Jason Baird, a cancer immunologist and staff research scientist at Providence Portland Medical Center in Oregon, told Portland’s KGW8 channel. “And then you get your booster, and then you see it take off again.”
The number of mothers participating was very limited, Bin-Nun noted, and the study has yet to be peer-reviewed, but so far the data seen, as in other preliminary studies, all point in the same direction.
While further research and data is necessary, Bin-Nun said, it is safe to assume that mothers who recovered or were vaccinated both during pregnancy and while nursing are likely passing antibodies to their children.
“Babies receive anti-bodies during pregnancy through the placenta, as well as during lactation, and there is no reason to believe that this is not true also for COVID,” said Bin-Nun. “There is only what to gain to get vaccinated during pregnancy.”
The recommendation in Israel is that all who are expecting a baby and are in their second or third trimesters should get vaccinated.
“Many women have been vaccinated in Israel, and no adverse effect has been detected,” Bin-Nun said. “In the NICU, we see how horrible the consequences of giving birth to a premature infant because of COVID can be. The alternative of getting vaccinated is very reassuring: this way the baby can receive protection both during pregnancy and after pregnancy.”
Contrary to the over-the-counter formula, human milk is a very versatile, adapting product, able to reflect the immune and hormonal status of the mother, she said.
“The more breast milk the baby receives, the higher the amount of antibodies,” said Bin-Nun. She strongly urged all mothers to nurse their children in order to protect them from infections, including COVID-19.
“Our gold standard for the first six months is only breastfeeding,” she concluded.