The Pfizer/BioNTech and Moderna Covid-19 vaccines are effective in pregnant and lactating women, who can pass 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 looked at 131 women who received either the Pfizer/BioNTech or Moderna Covid-19 vaccine. Among the participants, 84 were pregnant, 31 were lactating and 16 were not pregnant or lactating. Samples were collected between Dec. 17, 2020 and March 2, 2021.
The vaccine-induced antibody levels were equivalent in pregnant and lactating women, compared to non-pregnant women. The 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 women passed protective antibodies to their newborns, measured in breast milk and the placenta. Alter said additional research is needed to understand how long those protective antibodies last in newborns.
The findings are in line with recent research, though this is the largest study on vaccines in pregnant women, to date. Pregnant and lactating women were not included in the initial clinical trials of the vaccines.
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 track 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.