AZ Exercises Caution With COVID Vaccine Safety Pause As Questions Remain Over Vector

AstraZeneca’s decision to place a voluntary pause on all trials of its COVID-19 vaccine candidate after a single patient experienced an “unexplained illness” in the UK Phase III trial is being seen as prudent in a fast-moving field, as concerns are raised over the safety of its adenovirus vector.

The adverse event in question has still to be confirmed by the company but reports in The New York Times suggest that it was transverse myelitis (TM), a rare immune-mediated inflammation which causes neural injury to the spinal cord. The condition usually has autoimmune origins, and has been observed in earlier vaccine studies