AstraZeneca’s COVID19 Vaccine Trial Paused Over Safety Concerns

the staff of the Ridgewood blog

Oxford UK, The Phase 3 clinical trial for AstraZeneca’s candidate SARS-CoV-2 vaccine (developed in collaboration with Oxford University) has been paused following the identification of a serious adverse event in one of the participants. Neither AstraZeneca nor Oxford University have yet disclosed details of the adverse event, which reportedly occurred in the UK; however, The New York Times reports that the patient developed transverse myelitis. It has not yet been determined whether the condition was associated with the vaccine. An earlier clinical trial for the AstraZeneca vaccine was also paused following the diagnosis of transverse myelitis in a participant, but the trial resumed after a safety review determined that the condition was not related to the vaccine.

These types of holds on Phase 3 trials are not uncommon. In a statement, AstraZeneca explained this hold was a routine action after identifying an unexplained illness during the course of the trial. AstraZeneca announced that independent experts will examine the vaccine’s safety data before determining the next steps. Phase 3 trials are designed to identify less common adverse events by recruiting tens of thousands of participants. Because these rarer side effects occur infrequently, they may not have been detected in smaller Phase 1/2 trials.