Pfizer drip feeds data from its pregnancy trial of covid-19 vaccine

Analysis of the data so far shows the trial was underpowered, poorly designed and incomplete.

In January 2021, in the absence of any human data in pregnancy, the CDC stated on its website that mRNA vaccines were “unlikely to pose a specific risk for people who are pregnant.”

Former CDC director Rochelle Walensky backed it up with a full-throated endorsement of covid-19 vaccination in pregnancy. 

“There is no bad time to get vaccinated,” said Walensky.

“Get vaccinated while you're thinking about having a baby, while you're pregnant with your baby or after you've delivered your baby,” she added.

Behind the scenes however, Pfizer was scrambling to conduct a clinical trial of its vaccine in pregnant women.

By February 2022, Pfizer revealed it still did “not yet have a complete data set.” Its statement read:

“The environment changed during 2021 and by September 2021, COVID-19 vaccines were recommended by applicable recommending bodies (e.g., ACIP in the U.S.) for pregnant women in all participating/planned countries, and as a result the enrollment rate declined significantly.”

This month, Pfizer finally posted some trial results on clinicaltrials.gov. 

The data do not appear in a peer-reviewed journal or a pre-print, nor has it been submitted to the FDA for evaluation.

I spoke with experts who have analysed the data with a fine-tooth comb and made some alarming observations.