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Moderna, Pfizer vaccines safe during pregnancy, study finds

Study: COVID vaccines safe during pregnancy
CDC study: Pfizer, Moderna COVID vaccines safe during pregnancy 07:10

There's no evidence to suggest that the Pfizer and Moderna COVID-19 vaccines pose risk during pregnancy, according to a preliminary report from researchers at the Centers for Disease Control and Prevention. The results are part of the biggest study yet on COVID-19 vaccine safety among pregnant people.

The peer-reviewed paper published Wednesday by The New England Journal of Medicine used self-reported data from more than 35,691 people who were either pregnant or soon to become pregnant. After getting the shot, some reported typical vaccine side effects — pain at the injection site, fatigue, headaches and muscle aches — but researchers say the data "did not show obvious safety signals." The study noted the findings were preliminary and only covered the first 11 weeks of the U.S. vaccine rollout, between December 14, 2020, and February 28, 2021.

The results published this week were an extension of a study presented by the CDC's Advisory Committee on Immunization Practices last month, which also found no safety concerns during pregnancy.

Pharmaceutical companies didn't include pregnant people during clinical trials of the COVID-19 vaccines, leaving doctors and families initially unsure whether the jab would be safe for those expecting. But such trials are now underway, and growing evidence suggests the vaccine is as safe for pregnant patients as it is for non-pregnant individuals. The American College of Obstetrics and Gynecologists, a leading professional medical organization, recommends that COVID-19 vaccines not be withheld from pregnant or breastfeeding patients, and that guidance has been echoed by the CDC.

Pregnant people are particularly vulnerable to more severe illness from COVID-19. According to data published by the CDC, those who contract the virus during pregnancy are more likely to be hospitalized and face a higher risk of death.

Wednesday's paper used data collected through three methods: V-safe, a CDC-sponsored program that collects vaccine side-effect data using smartphones; the v-safe pregnancy registry; and Vaccine Adverse Event Reporting System (VAERS), a longstanding joint surveillance effort between the CDC and the Food and Drug Administration that collects adverse vaccine reports. All of the data used in the research was self-reported.

According to the study, pregnant patients reported pain at the vaccine's injection site at a slightly higher rate than their non-pregnant peers, but were less likely to say they experienced headache, muscle pain, chills, and fever. Among the 827 study participants who completed their pregnancy, the rate of miscarriage was consistent with pregnancy outcomes prior to the pandemic, according to the researchers.

However, no data yet exists on pregnancy outcomes for patients given the vaccine in their first trimester.

Researchers acknowledged that "more longitudinal follow-up, including follow-up of large numbers of women vaccinated earlier in pregnancy, is necessary to inform maternal, pregnancy, and infant outcomes."

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