AstraZeneca Covid-19 vaccine study put on hold after report of a suspected adverse reaction

A large, Phase 3 study of a Covid-19 vaccine being co-developed by AstraZeneca and the University of Oxford has been put on hold after a participant in the U.K. was suspected to have developed a serious adverse reaction. The vaccine, currently a frontrunner alongside eight other vaccine candidates also in Phase 3 trials, is being tested at dozens of sites across the U.S. AstraZeneca said it had voluntarily placed the trial on hold. A company spokesperson told STAT that the company's “standard review process triggered a pause to vaccination to allow review of safety data,” adding that AstraZeneca is “working to expedite the review of the single event to minimize any potential impact on the trial timeline.” The nature of the adverse reaction was also not immediately known, although the participant in question is expected to recover.