Slow enrollment delays study of Pfizer vaccine in pregnant women

A Pfizer and BioNTech study to determine how the COVID-19 vaccine affects pregnant women has been delayed due to slow enrollment and new vaccination guidelines.

“We have stopped enrollment in U.S. because of recommendations encouraging vaccination of pregnant women and we are exploring options regarding study sites outside the US where such recommendations do not exist,” a Pfizer spokesperson said in an emailed statement to The Hill on Wednesday.

The Wall Street Journal on Wednesday reported that Pfizer launched its pregnancy trial in February with strong enrollment given the limited supply of vaccines that the U.S. had at the time. Pfizer later closed enrollment at some U.S. sites after the Centers for Disease Control and Prevention (CDC) recommended that pregnant women get vaccinated.

The Wall Street Journal also reported that expectant mothers were less inclined to participate in the trial given the possibility of receiving a placebo shot instead of a vaccine.

Pfizer’s initial announcement of the study said results would be submitted in the second quarter of 2021. The company now expects results in early 2022, the Journal reported.

Earlier this week, Pfizer-BioNTech announced that its COVID-19 vaccine was safe for use in children ages 5 to 11. The announcement followed news that the Food and Drug Administration recommended a third dose of the company’s vaccine for people over age 65 and those in certain high-risk groups.