Drug makers and U.S. regulators plan to start clinical trials in January that will test the safety of Covid-19 vaccines in pregnant women and young children, said Dr. Anthony Fauci, director of the National Institute for Allergies and Infectious Diseases.
These two groups were excluded from the initial clinical trials of Covid-19 vaccines until researchers were able to determine that the vaccine was relatively safe in healthy adults before testing in more susceptible populations.
Fauci noted on Thursday in a discussion sponsored by Columbia University on Thursday that pregnant women have not been included in clinical trials of Covid vaccines. It is not clear whether the omission means that pregnant women cannot receive an approved vaccine until further safety data are collected.
Studies on pregnant women will be done in later studies, he said.
"It won't necessarily concern efficacy, but we will be investigating safety and immunogenicity to bridge efficacy in the adult non-pregnant population," he said at Columbia University's Grand Rounds 2020 event. "The same goes for the pediatric population. These studies are expected to begin in mid-to-late January."
Doctors have noted an increased risk of complications in pregnant women who contract Covid-19, said Aron Hall, chief of Covid at the CDC.
"The first indication is that there may be a higher risk of premature delivery," he said Thursday on the FDA's Advisory Committee on Vaccines and Related Biological Products.
While young children are less likely to die from Covid-19 when they get it, there is an increased risk of developing what is known as multisystem inflammatory syndrome in children, or MIS-C, researchers have found. It is an inflammatory disease that can affect several organ systems throughout the body, including the heart, lungs, and brain.
Fauci's comments came as the FDA's Vaccine Advisory Board is weighing whether to recommend Pfizer's emergency approval of the Covid vaccine.
Data on Pfizer's vaccine has shown it to be remarkably effective in preventing disease among study participants, and the FDA is expected to approve emergency use as early as Friday.
The UK drug and health products regulator, which last week approved Pfizer's vaccine for wide use in adults, warned against giving it to pregnant or breastfeeding women.
Dr. Doran Fink, associate director of the FDA's vaccines and related products division, said Thursday there was "very limited data on use in pregnancy".
"We recognize that among the groups first prioritized for vaccine use under an EEA, there will be many women of childbearing potential, including women who are knowingly or unknowingly pregnant," he said on the Meet on Thursday afternoon. "We really do not have any data that suggest any specific risks to pregnant women or the fetus, but neither do we have any data that would justify a contraindication to use in pregnancy at this time."
He added that pregnant women and women of childbearing age are "free to make their own choice" under what is known as an emergency permit.
The FDA advised manufacturers, including Pfizer, to conduct DART studies or developmental and reproductive toxicity studies before including pregnant women and "women of childbearing potential who do not actively avoid pregnancy" in vaccine studies, Pfizer said – Speaker Jerica Pitts CNBC. DART studies are done in animals to assess the potential risks of a vaccine to a developing fetus.
"Pfizer recognizes that the development of a potential SARS-CoV-2 vaccine for wide use is critical to halting the pandemic, including potential use in pregnant women," Pitts said in a statement. "Pfizer is currently conducting DART studies and plans to provide available data to the agency."
Pfizer admitted at the FDA's vaccine meeting Thursday that according to a presentation there was no information about the effects of the vaccine on pregnant women. Company officials told the advisory board that they expected preliminary results from its DART studies by mid-December.
The company also noted that there is also a lack of information on the effects of the vaccine in children and adolescents under the age of 16. The FDA advisory panel will vote on its non-binding recommendation later Thursday, and the FDA is expected to do so soon.
– CNBC's Amanda Macias contributed to this report.