AstraZeneca paused the ongoing, randomized controlled trial of the AstraZeneca Oxford coronavirus vaccine, AZD1222, to allow an independent committee to review the safety data for an unexplained illness that occurred in the UK Phase III trial.
In an official statement, AstraZeneca described the pause as a “routine action” that occurs “whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials.” The company also said it is working to expedite the review process to minimize “any potential impact on the trial timeline.”
According to AstraZeneca, AZD1222 was co-invented by the University of Oxford and its spin-out company, Vaccitech. It uses a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein. After vaccination, the surface spike protein is produced, priming the immune system to attack the SARS-CoV-2 virus if it later infects the body.
