New technology, uncertain risks
At the time COVID-19 vaccines were being developed, scientists had very little experience using mRNA vaccines in pregnant women, said Jacqueline Miller, MD, a senior vice president involved in vaccine research at Moderna.
“When you study anything in pregnant women, you have two patients, the mom and the unborn child,” Dr. Miller said. “Until we had more safety data on the platform, it wasn’t something we wanted to undertake.”
But Dr. Offit noted that vaccines have a strong record of safety in pregnancy and he sees no reason to have excluded pregnant people. None of the vaccines currently in use – including the chickenpox and rubella vaccines, which contain live viruses – have been shown to harm fetuses, he said. Doctors routinely recommend that pregnant people receive pertussis and flu vaccinations.
Dr. Offit, the coinventor of a rotavirus vaccine, said that some concerns about vaccines stem from commercial, not medical, interests. Drug makers don’t want to risk that their product will be blamed for any problems occurring in pregnant people, even if coincidental, he said.
“These companies don’t want bad news,” Dr. Offit said.
In the United States, health officials typically would have told expectant mothers not to take a vaccine that was untested during pregnancy, said Dr. Offit, a member of a committee that advises the Food and Drug Administration on vaccines.
Due to the urgency of the pandemic, health agencies instead permitted pregnant people to make up their own minds about vaccines without recommending them.
Women’s medical associations were also hampered by the lack of data. Neither the American College of Obstetricians and Gynecologists nor the Society for Maternal-Fetal Medicine actively encouraged pregnant people to be vaccinated until July 30, 2021, after the first real-world vaccine studies had been published. The CDC followed suit in August of 2021.
“If we had had this data in the beginning, we would have been able to vaccinate more women,” said Kelli Burroughs, MD, the department chair of obstetrics and gynecology at Memorial Hermann Sugar Land Hospital near Houston.
Yet anti-vaccine groups wasted no time in scaring pregnant people, flooding social media with misinformation about impaired fertility and harm to the fetus.
In the first few months after the COVID-19 vaccines were approved, some doctors were ambivalent about recommending them, and some still advise pregnant patients against vaccination.
An estimated 67% of pregnant people today are fully vaccinated, compared with about 89% of people 65 and older, another high-risk group, and 65% of Americans overall. Vaccination rates are lower among minorities, with 65% of expectant Hispanic mothers and 53% of pregnant African Americans fully vaccinated, according to the CDC.
Vaccination is especially important during pregnancy, because of increased risks of hospitalization, ICU admission, and mechanical ventilation, Dr. Burroughs said. A study released in February from the National Institutes of Health found that pregnant people with a moderate to severe COVID-19 infection also were more likely to have a C-section, deliver preterm, or develop a postpartum hemorrhage.
Black moms such as Ms. Slade were already at higher risk of maternal and infant mortality before the pandemic, because of higher underlying risks, unequal access to health care, and other factors. COVID-19 has magnified those risks, said Dr. Burroughs, who has persuaded reluctant patients by revealing that she had a healthy pregnancy and child after being vaccinated.
Ms. Slade said she has never opposed vaccines and had no hesitation about receiving other vaccines while pregnant. But she said she “just wasn’t comfortable” with COVID-19 shots.
“If there had been data out there saying the COVID shot was safe, and that nothing would happen to my baby and there was no risk of birth defects, I would have taken it,” said Ms. Slade, who has had type 2 diabetes for 12 years.