The analysis, based on medical records of nearly 14 million U.S. patients since coronavirus immunization became available, found that pregnant people who are vaccinated have the greatest risk of developing covid among a dozen medical states, including being an organ transplant recipient and having cancer.
The findings come on top of research showing that people who are pregnant or gave birth recently and became infected are especially prone to getting seriously ill from covid-19. And covid has been found to increase the risk of pregnancy complications, such as premature births.
The Centers for Disease Control and Prevention has been urging people to get coronavirus shots before or during pregnancy, seeking to dispel fear — widespread in some communities, without scientific basis — that those vaccinations could be harmful. As of March, nearly 70 percent of people who were pregnant had been vaccinated before or during their pregnancy, according to federal data, though disparities persist among racial and ethnic groups.
The new study goes beyond what has previously been understood, suggesting that even pregnant people who are fully vaccinated tend to have less protection from the virus than many other patients with significant medical problems.
“If you are fully vaccinated, that’s magnificent,” said a lead author of the study, David R. Little, a physician who is a researcher at Epic, a Wisconsin company that maintains electronic patient records for nearly 1,000 hospitals and more than 20,000 clinics across the country. “But if you are fully vaccinated and become pregnant, you remain at higher risk of acquiring covid.”
Little said the findings buttress CDC recommendations that additional precautions against the virus should be taken during pregnancy, such as wearing masks and maintaining safe distances. He said the study also suggests that health-care workers should “be on the lookout” for symptoms and encourage testing to detect the virus early, when it is easier to treat.
The data also raises scientific questions that warrant further research into how best to protect pregnant individuals and their babies from infection, according to public health leaders and specialists in pregnancy.
“To me, the most important question the new study raises is, is there an increased rate of severe illness and death in pregnant patients after a certain period of time” following vaccination, said Brenna L. Hughes, vice chair for obstetrics and quality at the Duke University School of Medicine Department of Obstetrics and Gynecology.
“I have not admitted a single vaccinated patient to the ICU. Every one has been unvaccinated,” Hughes said. “Of course, we worry as boosters wane.” There is no research evidence on whether the protection conferred by coronavirus shots lasts as long for pregnant people as it does for others.
The study did not assess how sick the patients became when they were infected with covid after having been vaccinated.
Georges C. Benjamin, executive director of the American Public Health Association, said the Epic findings point to a need to understand whether it is most helpful to be vaccinated before becoming pregnant or soon afterward, the most useful time interval between shots and what dosage is best. Those questions apply, he said, to the well-being of pregnant patients and their babies.
“There’s lots of good science to be had here,” Benjamin said. But for now, he added, “people shouldn’t panic. You are not getting sick because of the vaccine. It argues that you probably need a little more of the vaccine.”
The analysis was based on Epic medical records from 13.8 million patients between January 2021, when the first people in the United States were fully vaccinated and had enough time to develop immunity, and late January this year. Little and…
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