ATLANTA (CNN) – COVID-19 Pfizer / BioNTech and Moderna vaccines are effective in pregnant and lactating women who can transmit protective antibodies to newborns, according to research published Thursday in the American Journal of Obstetrics and Gynecology.
Researchers at Massachusetts General Hospital, Brigham and Women’s Hospital and the Ragon Institute of MGH, MIT and Harvard analyzed 131 women who received either the Pfizer / BioNTech vaccine or the Modern COVID-19. Of the participants, 84 were pregnant, 31 were breastfeeding and 16 were not pregnant. The samples were collected between December 17, 2020 and March 2, 2021.
Vaccine-induced antibody levels were equivalent in pregnant and lactating women compared to non-pregnant women. Antibody levels were “strikingly higher” than those resulting from coronavirus infection during pregnancy, the team noted.
“These vaccines seem to work incredibly effectively in these women,” said one of the researchers, Galit Alter, a professor of medicine at the Ragon Institute.
In addition, the team found that the women transmitted protective antibodies to their newborns, measured in breast milk and placenta.
“Almost all mothers receive a fairly decent level of antibodies for their babies,” said Alter, who added that further research is needed to understand how long these protective antibodies last in newborns.
Participants used the US Centers for Disease Control and Prevention’s V-safe tool, which allows people who have received a COVID-19 vaccine to monitor their reaction. 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 levels of antibodies 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 that this particular type of antibody can be transferred more effectively to children for a longer period of time.
“There is some reason to believe that having higher levels of immunity to IgA could be more protective,” Alter noted. She said further research into this finding could help inform policy decisions about vaccines used for pregnant populations.
Recent research has similarly found that mRNA vaccines generate antibodies in pregnant women that can be transferred to their children, although this is the largest study of vaccines in pregnant women to date. Pregnant and lactating women have not been included in the initial clinical trials of vaccines.
This is an urgent need, because we are not only protecting one person in this vaccination effort, but we are protecting two people at the same time.
–Galit Alter, professor of medicine at the Ragon Institute
With no data available to help inform pregnant women’s decisions about vaccination against COVID-19, Alter said researchers and expectant mothers – especially health workers – have stepped up to fill the gap.
“MGH and Brigham began talking to health workers who were eligible for vaccination, who were also pregnant, and set up a study to empower pregnant women with the ability to track their responses, but also to develop data that could essentially help the whole globe address 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 / supplier perspective and from the community,” Alter said. “It was inspiring.”
According to the CDC, people pregnant with COVID-19 have an increased risk of severe disease and may be at increased risk of adverse outcomes, such as premature birth. The CDC says it hopes to study the safety of vaccines in about 13,000 pregnant women for each of the three authorized coronavirus vaccines. The agency will use a specific register of safe pregnancy in V, which has registered about 3,612 pregnant women, starting March 22.
“This is an urgent need, because we are not just protecting one person in this vaccination effort, we are protecting two people at the same time,” Alter said.
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