AstraZeneca Resumes U.S. COVID-19 Vaccine Trial

The FDA has given AstraZeneca the all-clear to restart its late-stage U.S. vaccine trial after wrapping up its safety review.

The UK drugmaker announced its resumption of the phase 3 trial Friday immediately after the FDA authorized the restart. The U.S. trial of AZD1222 had been paused for more than a month in response to an investigation into a safety incident, although AZ’s trials in other countries were allowed to resume earlier (DID, Oct. 16).

Neither AstraZeneca nor the agency shared details about the findings of the safety review that was reportedly linked to two suspected adverse events. The company merely said the agency “concluded it was safe to resume the trial,” while the agency issued no immediate statement.

According to reports that circulated Friday, the FDA’s safety investigation looked into two participants who suffered possible neurological side effects, one of whom was in the UK, and found AZ’s vaccine did not cause the incidents – but it also couldn’t conclude definitively that the vaccine had no involvement.

AZ CEO Pascal Soriot said the company believes it will see results from the trials “later this year” depending on the rate of coronavirus infections in the areas where the trials are being run. Soriot described the safety review as a sign that regulators are using necessary caution toward COVID-19 vaccine research even as companies are nearing the finish line, though he noted it’s not uncommon for participants to get sick in large-scale vaccine trials.

“We should be reassured by the care taken by independent regulators to protect the public and ensure the vaccine is safe before it is approved for use,” he said.

Andrew Pollard, the chief investigator for the global clinical trials of the vaccine developed at   Oxford University, said that resuming the U.S. trial will enable a combined enrollment of 50,000 participants globally. So far, more than 20,000 people have been recruited into the late-stage trials, he said.

The restart was a welcome boost for AZ following the death last week of a patient in Brazil’s phase 3 trial of the vaccine. The patient was reportedly in the trial’s placebo group, however, and AZ said that trial would not be impacted (DID, Oct. 22). — James Miessler