AstraZeneca reports that is has temporarily paused its clinical trials for its COVID-19 vaccine, AZD1222, to allow an independent committee to review the safety data of a single event of an unexplained illness that occurred in a Phase III trial in the UK. The company said the incident was found during standard review of the trial.

“This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials,” said AstraZeneca in a September 9, 2020 statement. “In large clinical trials, illnesses will happen by chance and must be independently reviewed. AstraZeneca is working to expedite the review of the single event to minimize any potential impact on the trial timeline. We are committed to the safety of our participants and the highest standards of conduct in our trials.”

Prior to the announcement of the voluntary trial pause, clinical development of AZD1222 was progressing globally with late-stage clinical trials ongoing in the UK, Brazil, and South Africa, with trials planned to start in Japan and Russia (as reported by the company on August 31, 2020). These trials, together with a US Phase III clinical trial, were planned to enroll up to 50,000 participants globally. Results from the late-stage trials were anticipated later this year (2020), depending on the rate of infection within the clinical trial communities.

AZD1222 was co-invented by the University of Oxford and its spin-out company, Vaccitech, and licensed to AstraZeneca. 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.

AstraZeneca was one of nine biopharmaceutical companies developing COVID-19 vaccines that issued a safety pledge this week (September 8, 2020) as part of an united commitment to uphold the integrity of the scientific process as they work toward potential global regulatory filings and approvals of the first COVID-19 vaccines. See related story.

Source: AstraZeneca