Clinical Trial of AstraZeneca COVID-19 Vaccine Paused After Illness

WEDNESDAY, Sept. 9, 2020 -- A "potentially unexplained" illness in a participant has led AstraZeneca to halt a late-stage clinical trial of its COVID-19 vaccine.

The company is investigating whether the illness may be a side effect of the vaccine, the Associated Press reported. The pause in the study covers the United States and other countries where the vaccine is being tested. The health news site STAT said the possible side effect occurred in the United Kingdom, the AP reported.

"We are working to expedite the review of the single event to minimize any potential impact on the trial timeline," AstraZeneca said in a statement.

Large, final-stage clinical trials of two other COVID-19 vaccines are underway in the United States, one from Moderna and the other from Pfizer and BioNTech. Those two vaccines work differently than the AstraZeneca vaccine, the AP reported.