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



According to the United States Centers for Disease Control and Prevention, pregnant women with Covid-19 have an increased risk of serious illness and an increased risk of adverse outcomes, such as premature labor. The study, along with existing research showing that mRNA vaccines are effective in pregnant and breastfeeding women, suggests that the benefits of the vaccines outweigh the risks.

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

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 had received an mRNA vaccine. They found 827 completed pregnancies and 115 (13.9%) suffered a miscarriage, while 712 (86.1%) resulted in a live birth. Premature births occurred in 9.4% of participants and only 3.2% of these births were of small gestational age. No neonatal deaths have been reported.

There were 221 pregnancy-related adverse events 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 among people vaccinated against Covid-19 who had a terminated pregnancy were similar to the incidences reported in studies involving pregnant women conducted before the pandemic. of Covid-19.

The study also looked at the side effects of vaccines during pregnancy. The researchers found that the most common side effect of the vaccine was pain at the injection site, which seemed to occur more frequently in vaccine recipients who were pregnant. However, headache, muscle pain, chills, and fever have been reported less frequently by pregnant women.

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

“Continuous monitoring is needed to further assess maternal, pregnancy, newborn and infant outcomes associated with maternal Covid-19 vaccination, including in the early stages of pregnancy and during the preconception period,” the researchers wrote. “Meanwhile, current data can help inform decision-making about immunization for pregnant women and their health care providers.

Protection of mothers and newborns

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

Researchers at Massachusetts General Hospital, Brigham and Women’s Hospital, and the Ragon Institute of MGH, MIT, and Harvard examined 131 women who received the Pfizer / BioNTech or Moderna Covid-19 vaccine. Of the participants, 84 were pregnant, 31 breastfeeding, and 16 were not pregnant or breastfeeding. Samples were taken between December 17, 2020 and March 2, 2021.

Vaccine-induced antibody levels were equivalent in pregnant and lactating women compared to non-pregnant women. The antibody levels were “remarkably higher” than those resulting from coronavirus infection during pregnancy, the team noted.

“These vaccines appear to work incredibly effectively in these women,” said one of the researchers, Galit Alter, professor of medicine at the Ragon Institute.

Additionally, the team found that women pass protective antibodies to their newborns, measured in breast milk and placenta. Alter said more research is needed to understand how long these 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 transferred to babies more effectively, over a longer period of time.

“There is reason to believe that having higher IgA immunity levels might be more protective,” noted Alter.


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