Boston researchers find COVID-19 antibodies in babies born to vaccinated mothers

There is new information for pregnant women considering a COVID-19 vaccine. Boston researchers say they now have solid data that they offer protection not just for moms, but for their babies, too.


"There is a precedent for using vaccines to actually promote the health and safety of women and babies," said Dr. Andrea Edlow, maternal-fetal medicine attending physician at Massachusetts General Hospital.

Edlow said because pregnant women were not included in the COVID-19 vaccine trials, though some did become pregnant while the studies were underway, there is limited data.

She and her Boston colleagues hope to change that. They've just submitted a study of immune response in pregnant women who received either the Pfizer or Moderna options, the mRNA vaccines.

The researchers looked at 131 women from last December through the end of February. Eighty-four were pregnant, 31 were breastfeeding and 16 were not pregnant. The antibody response was the same in all three groups.

"The vaccine promotes an excellent antibody response. We compared the antibody levels that pregnant women who got COVID itself had after COVID infection and we found actually that the vaccine antibody levels are much higher," Edlow said.

Encouragingly, detectable levels of antibodies were passed along to ten babies born during the study period.

"So far it seems to be working really similarly to other vaccines we give to other pregnant women that we expect to give antibodies to the babies through cord and through breast milk," Edlow said.

Edlow said this finding should be reassuring for pregnant women considering the vaccine and there's another question the team continues to study.

"It will be interesting to see if you get vaccinated in the first trimester or the second trimester, what is the passage of antibodies through to the baby's umbilical cord? Is it enhanced by getting vaccinated earlier versus later?"

This trial wasn't designed to look at the safety considerations surrounding the vaccines but Edlow said there's nothing to suggest it's not safe to receive one of the vaccines.

That's based on all of the national data, from the Centers for Disease Control and Prevention, from the clinical trials as well as information gathered since vaccinations outside the trials began.