- Researchers studied 131 women who received either the Pfizer or Moderna COVID-19 vaccines.
- The pregnant or lactating women had as strong an immune response as the nonpregnant women.
- Their babies developed high levels of disease-fighting antibodies.
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The COVID-19 vaccines by Pfizer and Moderna are effective in pregnant women, bolstering their immune response to the disease and even passing protective antibodies to their babies, according to a new preprint study.
The study, published Thursday in the American Journal of Obstetrics and Gynecology, looked at 131 women who received one of the two vaccines between December and March, of whom 84 were pregnant and 31 were lactating.
Researchers, from centers including Harvard, MIT, and Brigham and Women’s Hospital, found pregnant and lactating women had as strong an immune response to the vaccines as the 16 women who were not pregnant or lactating.
What’s more, they found the vaccines were much better than exposure to the coronavirus at giving babies secondary antibodies. Testing umbilical cord blood and the placenta, they found babies born to women who received the vaccine had “strikingly higher” levels of COVID-fighting antibodies than babies born to women who previously had COVID-19, the researchers wrote.
The research supports vaccinating pregnant women
The research adds to a growing body of research that indicates getting a COVID-19 vaccine is a good idea for pregnant women. In March, the CDC said there were no adverse results in its study on 30,000 vaccinated pregnant women across the US.
Pregnant people were not included in the clinical trials studying any of the COVID-19 vaccines. As a result, when US regulators authorized the first COVID-19 vaccine in early December (by Pfizer BioNTech), health officials said it was a decision for pregnant women to make with their doctor.
As research mounts, that decision-making process is getting easier for pregnant people and OBGYNs, Dr. Andrea Edlow, a maternal-fetal medicine expert at Massachusetts General Hospital in Boston who co-authored the study, told NBC.
“This study is one piece of the puzzle that’s essential to try to give pregnant and lactating women evidence-based counseling around the vaccine,” Edlow said.
What we know about the Pfizer and Moderna shots in pregnancy
Studies are underway, both in clinical trial settings and real-world settings, as more and more pregnant people choose to get the shot.
Pending that data, the CDC notes that studies in pregnant animals found no safety issues tied to receiving mRNA vaccines – i.e. the vaccine technology used in both the Pfizer and Moderna COVID-19 shots.
There has been plenty of misinformation spread about mRNA vaccines, which uses messenger RNA (mRNA) to train the body to recognize the virus and mount an immune response.
Anti-vaccine activists like Robert F Kennedy, Jr. have promoted a myth that the vaccine interferes with DNA – a physiological impossibility since the vaccines do not enter your genetic material.
The American College of Obstetricians and Gynecologies (ACOG) issued an advisory to pregnant and lactating people debunking this myth: “These vaccines do not enter the nucleus and do not alter human DNA in vaccine recipients. As a result, mRNA vaccines cannot cause any genetic changes.”
Vaccines seem to protect babies, too
A small peer-reviewed study in January found that pregnant women vaccinated against COVID-19 passed antibodies onto their unborn babies.
In February, researchers said a baby born to a woman who had only received one of the two Moderna shots tested positive for protective antibodies.