ATLANTA (CNN) – The Pfizer / BioNTech and Moderna COVID-19 vaccines are effective in pregnant and nursing women, which can pass protective antibodies to newborns, according to research published Thursday in the American Journal of Obstetrics and Gynecology.
Researchers from Massachusetts General Hospital, Brigham and Women’s Hospital, and the Ragon Institute of MGH, MIT, and Harvard looked at 131 women who received the Pfizer / BioNTech or Moderna COVID-19 vaccine. Of the participants, 84 were pregnant, 31 breastfed and 16 were not pregnant. Samples were collected between December 17, 2020 and March 2, 2021.
The antibody levels induced by the vaccine were similar in pregnant and lactating women compared to non-pregnant women. Antibody levels were “markedly higher” than those resulting from coronavirus infection during pregnancy, the team noted.
“These vaccines appear to be incredibly effective in these women,” said one of the researchers, Galit Alter, a professor of medicine at the Ragon Institute.
In addition, the team found that women pass protective antibodies to their newborns, as measured in breast milk and the placenta.
“Nearly all mothers were given pretty decent levels of antibodies to their babies,” said Alter, adding that additional research is needed to understand how long those protective antibodies last in newborns.
Participants used the U.S. Centers for Disease Control and Prevention’s V-safe tool, which allows people who have received a COVID-19 vaccine to monitor their response. Alter said they found no evidence of more side effects or more intense side effects in pregnant and lactating women than in the general population.
While the team found similar antibody levels in women vaccinated with both vaccines, Alter said they found higher levels of IgA antibodies in pregnant women who received the Moderna vaccine. She said this particular type of antibody can be more efficiently transmitted to babies for a longer period of time.
“There is some reason to believe that having higher levels of IgA immunity could provide more protection,” noted Alter. She said additional research into this finding could help make policy decisions about which vaccines to use for pregnant populations.
Recent research has also shown that mRNA vaccines elicit antibodies in pregnant women that can be passed on to their babies, although this is the largest study of vaccines in pregnant women to date. Pregnant and nursing women were not included in the initial clinical studies of the vaccines.
This is an urgent need because we are not only protecting one person in this vaccination effort, we are also protecting two people at the same time.
–Galit Alter, a professor of medicine at the Ragon Institute
In the absence of data to help pregnant women make decisions about vaccination against COVID-19, Alter said researchers and new and expectant mothers – particularly health workers – filled the void.
MGH and Brigham started talking to the health care providers who were eligible for vaccination, who were also pregnant, and they created a study to allow pregnant women to monitor their responses, as well as to develop data that could essentially help the whole world approach vaccination and pregnancy for the first time in this collective way.
“It was really just a force to be reckoned with, both from an OB-GYN / provider perspective, but also from the community,” said Alter. “It was inspiring.”
According to the CDC, pregnant people with COVID-19 are at an increased risk of serious illness and may be at increased risk for adverse outcomes, such as premature birth. The CDC hopes to investigate vaccine safety in approximately 13,000 pregnant people for each of the three authorized coronavirus vaccines. The agency will use a specific V-safe pregnancy registry, which enrolled about 3,612 pregnant women on March 22.
“This is an urgent need because we are not only protecting one person in this vaccination effort, we are also protecting two people at the same time,” said Alter.
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