AstraZeneca halted vaccine trial after participant developed serious neurological symptoms

We now know what prompted AstraZeneca to halt a Phase 3 clinical trial for its Covid-19 vaccine: A woman in the U.K. developed symptoms consistent with a rare but serious spinal inflammatory disorder called transverse myelitis, STAT’s Adam Feuerstein reports.

During a private investor call yesterday morning, AstraZeneca CEO Pascal Soriot confirmed the woman had received the vaccine and not a placebo; he also confirmed that the trial had been halted once before, in July, after another participant experienced neurological symptoms. However, that volunteer wound up being diagnosed with multiple sclerosis — which was deemed unrelated to the Covid-19 vaccine.

One investor on the call said Soriot meant to reassure investors that AstraZeneca was taking the vaccine safety event seriously — and to help reverse the sharp decline in the company’s stock price.

“A vaccine that nobody wants to take is not very useful,” Soriot said.