Pfizer and Moderna Covid-19 vaccines do not appear to pose a serious risk during pregnancy, research shows

Pregnant women with Covid-19 are at an increased risk of serious illness and may be at increased risk for adverse outcomes, such as premature birth, according to the U.S. Centers for Disease Control and Prevention. The study, along with existing research showing that mRNA vaccines are effective in pregnant and lactating women, suggests that the benefits of the vaccines outweigh the risks.

The new study assessed data on 35,691 pregnant people between December 14, 2020 and February 28, 2021 from the CDC’s V-safe smartphone-based surveillance system, as well as data from the CDC’s Vaccine Adverse Event Reporting System (VAERS). All participants were pregnant and 16 to 54 years old.

The researchers followed a group within the V-safe system to collect more data on pregnancy outcomes and complications. This registry included 3,958 pregnant participants (out of 35,691) who received an mRNA vaccine. They found 827 completed pregnancies and 115 (13.9%) suffered a pregnancy loss, while 712 (86.1%) resulted in a live birth. Preterm birth occurred in 9.4% of the participants and only 3.2% of these births were of short gestational age. No neonatal deaths were reported.

221 pregnancy-related adverse events were reported to the CDC’s VAERS Registry, and 46 of them were miscarriages.

Although not directly comparable, the calculated proportions of adverse pregnancies and neonatal outcomes in subjects vaccinated against Covid-19 who had completed pregnancies were similar to incidents reported in studies of pregnant women conducted before the Covid. -19 pandemic. ”

The study also looked at the side effects of vaccines during pregnancy. Researchers found that the most common side effect of the vaccine was injection site pain, which appeared to be more common in vaccine recipients who were pregnant. However, headache, muscle aches, chills and fever were less commonly reported by pregnant people.

The researchers say more long-term studies are needed to assess the safety of the Covid-19 vaccine in pregnancy, and that this study should include follow-up with a large population being vaccinated early in pregnancy.

“Ongoing monitoring is needed to further assess maternal, gestational, neonatal and childhood outcomes associated with maternal Covid-19 vaccination, including at earlier stages of pregnancy and during the preconception period,” the researchers wrote. “Meanwhile, the current data may aid in decision-making about vaccination by pregnant individuals and their caregivers.”

Protection for mothers and newborns

In addition to being safe, research released last month showed that Moderna and Pfizer’s mRNA Covid-19 vaccines are also effective in protecting pregnant and nursing women – and their newborns. The study, published in the American Journal of Obstetrics and Gynecology that also used V-safe data, showed that mothers can pass protective antibodies to newborns.

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 were lactating and 16 were not pregnant or lactating. 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. Alter said additional research is needed to understand how long those protective antibodies last in newborns.

While the team found similar antibody levels in women vaccinated with each vaccine, 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.