Pfizer-BioNTech announced Thursday that the first participants of its global Covid-19 vaccine trial for pregnant women have received their first doses.
The Phase 2/3 trial will enroll about 4,000 healthy pregnant women age 18 or older, according to a news release from the company. They will be vaccinated during 24 to 34 weeks of gestation and receive two doses of the vaccine or placebo 21 days apart.
The first doses were administered to US participants. The trial will be conducted in nine countries: the United States, Canada, Argentina, Brazil, Chile, Mozambique, South Africa, UK and Spain.
“We are proud to start this study in pregnant women and continue to gather the evidence on safety and efficacy to potentially support the use of the vaccine by important subpopulations,” Dr. William Gruber, Pfizer’s senior vice president of vaccine clinical research and development, said in the release.
The company said the trial is designed to evaluate the vaccine in pregnant women, but also their infants, who will be monitored until they’re about six months old, for safety and for the transfer of potentially protective antibodies. Once an infant is born, Pfizer-BioNTech said trial participants will be unblinded and adults in the placebo group will receive the vaccine.
Currently, the US Centers for Disease Control and Prevention says pregnant people are at increased risk for severe illness from Covid-19, and there’s limited data about the safety of the vaccines for pregnant people. It suggests pregnant patients talk with their doctor to make the decision about whether to be vaccinated against Covid-19.