Pregnant women make up a large part of the country’s population who face high risks for severe COVID-19, but it’s unknown how safe it is for them to get a coronavirus vaccine.
Neither the Pfizer-BioNTech nor Moderna vaccine were tested in pregnant women: In fact, all women who tested positive on a pregnancy exam prior to beginning a clinical trial were excluded from participating.
Both companies have said its clinical trials have “insufficient” data to conclude its vaccines in pregnant and breastfeeding women are safe, but research to test the vaccines in this group is “planned,” according to the Centers for Disease Control and Prevention.
The CDC and the U.S. Food and Drug Administration have not officially recommended the vaccine for this population.
Still, infectious diseases and vaccine experts “believe they are unlikely to pose a risk for people who are pregnant” because of how the vaccine works, the CDC said.
The Pfizer-BioNTech and Moderna candidates both pump mRNA, a molecule that is already in your body, directly into muscles. This mRNA carries instructions that teach cells to produce antibodies against the coronavirus.
The vaccines do not inject live (weakened) virus or an inactivated (killed) virus, and therefore they cannot give someone COVID-19.
All the contents of the vaccine disappear after a couple of days as cells quickly break down the material, leaving only your immune system’s memory of the shot and its acquired protection against the coronavirus, according to the CDC.
“However, the potential risks of mRNA vaccines to the pregnant person and her fetus are unknown because these vaccines have not been studied in pregnant women,” the agency said.
That’s why the CDC says it’s up to pregnant women to choose if they want to get vaccinated, depending on decisions they make with their health care providers.
An FDA report on the Pfizer-BioNTech vaccine says that 23 pregnancies were reported after participants received their vaccine as part of the clinical trial — 12 of them in the group that got the vaccine and 11 in the group that got the placebo.
A separate report on the Moderna vaccine says 13 pregnancies were reported after vaccination, with six in the vaccine group and seven in the placebo group.
However, it’s too early for either company to know how the vaccine may have affected these women’s pregnancies. Researchers will continue to monitor them throughout the study, although no serious side effects have been reported to date.
At the same time, agency officials do not recommend taking a pregnancy test before getting a COVID-19 vaccine. Women of childbearing age also don’t have to avoid getting pregnant after getting the shot for fear of risks, the CDC added.
Although data are lacking for COVID-19 vaccine safety in lactating women or on breastfed infants, experts say the shot is “not thought to be a risk.”
Britain’s Joint Committee on Vaccination and Immunization, however, has taken a different stand.
It does not recommend women who may be pregnant or are planning a pregnancy within three months of a first dose to get the Pfizer-BioNTech vaccine, the only one authorized for emergency use in the country.
The vaccines are being tested in animals in the U.S. in studies called “developmental and reproductive toxicity studies,” or DART, a standard for testing medical products such as vaccines in pregnant women.
“We don’t know exactly what the efficacy is during pregnancy and what are the potential risks and or benefits,” Dr. Devika Maulik, an OB-GYN at the Truman Medical Center and Children’s Mercy Hospital in Missouri, told KMBC 9. “We think that it is likely safe, there’s just no data to show it.”
Maulik said that certain vaccines can help babies build an antibody response against viruses when given to the mother during her third trimester because it “can cross the placenta.”
“This has not been proven with the coronavirus vaccine, but it has been shown with other vaccines,” Maulik told the outlet.
The American College of Obstetricians and Gynecologists said it “recommends that COVID-19 vaccines should not be withheld from pregnant individuals who meet criteria for vaccination,” according to a Dec. 13 statement. “While safety data on the use of COVID-19 vaccines in pregnancy are not currently available, there are also no data to indicate that the vaccines should be contraindicated.”
What’s more, experts say the risks of getting COVID-19 may outweigh the risks of getting a vaccine.
Studies have shown that women battling coronavirus during pregnancy have a 25% higher risk of premature birth than healthy women, and they face a 70% increased risk of dying compared to non-pregnant women, McClatchy News reported.
Invasive ventilation, intensive care unit admission and ECMO were also more common among pregnant than non-pregnant women. ECMO stands for extracorporeal membrane oxygenation. It’s a procedure that removes blood from your body, runs it through a machine that clears it of carbon dioxide, and inserts oxygen-rich blood back into the body.