AstraZeneca has “voluntarily paused” late-stage trials of the highly-anticipated COVID-19 vaccine it is developing with the University of Oxford after one of the study volunteers developed an unexplained illness, the company said on Wednesday.
The AstraZeneca-Oxford vaccine is seen as one of the most promising of coronavirus vaccine candidates currently under development.
“As part of the ongoing randomized, controlled global trials of the Oxford coronavirus vaccine, our standard review process was triggered and we voluntarily paused vaccination to allow review of safety data by an independent committee,” said Michele Meixell, the company’s spokeswoman.
“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.”
Health news website Stat News earlier reported that the trial would be suspended because a volunteer had suffered a severe adverse reaction to the drug.
AstraZeneca said that in large trials, illnesses sometimes occur in participants by chance, but that the issue had to be reviewed independently.
“We are working to expedite the review of the single event to minimise any potential impact on the trial timeline,” Meixell said.
The drug is in trials involving thousands of people in the United States, Brazil, South Africa and the UK, where the patient who fell ill is.
Julie Fischer, an associate research professor in the Department of Microbiology and Immunology at the Center for Global Health Science and Security at Georgetown University, says such a pause was “part of the process” of drug development and clinical trials.
“For a pause, the event would need to be serious; something related to the heart, lungs, kidneys or other part of the body’s health system that required medical attention and was sufficiently serious to merit a pause to this very important vaccine trial in order to make sure it is safe, and that the adverse effect is not due to the vaccine itself.”