UK pharmaceutical company AstraZeneca on Saturday said it has resumed clinical trials for the coronavirus vaccine, days after the trials were halted due to a volunteer falling ill.
"Clinical trials for the AstraZeneca Oxford coronavirus vaccine, AZD1222, have resumed in the UK following confirmation by the Medicines Health Regulatory Authority (MHRA) that it was safe to do so," the company said in a statement.
Late-stage studies of AstraZeneca's COVID-19 vaccine candidate were temporary paused after a volunteer fell sick.
It said that on 6 September, the standard review process triggered a voluntary pause to vaccination across all global trials to allow review of safety data by independent committees, and international regulators. “The UK committee has concluded its investigations and recommended to the MHRA that trials in the UK are safe to resume,” the company said in a statement.
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Late last month, AstraZeneca began recruiting 30,000 people in the US for its largest study of the vaccine. It also is testing the vaccine, developed by Oxford University, in thousands of people in Britain, and in smaller studies in Brazil and South Africa.
Two other vaccines are in huge, final-stage tests in the United States, one made by Moderna Inc. and the other by Pfizer and Germany's BioNTech. Those two vaccines work differently than AstraZeneca's, and the studies already have recruited about two-thirds of the needed volunteers.
Temporary holds of large medical studies aren't unusual, and investigating any serious or unexpected reaction is a mandatory part of safety testing.
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It's likely the unexplained illness was serious enough to require hospitalization and not a mild side effect such as fever or muscle pain, said Deborah Fuller, a University of Washington researcher who is working on a different COVID-19 vaccine that has not yet started human testing.
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"This is not something to be alarmed about," Fuller said. Instead, it's reassuring that the company is pausing the study to figure out what's happening and carefully monitoring the health of study participants.
Dr Ashish Jha of Brown University said via Twitter that the significance of the interruption was unclear but that he was "still optimistic" that an effective vaccine will be found in the coming months.
"But optimism isn't evidence," he wrote. "Let's let science drive this process."
Angela Rasmussen, a virologist at Columbia University in New York, tweeted that the illness may be unrelated to the vaccine, "but the important part is that this is why we do trials before rolling out a vaccine to the general public".
During the third and final stage of testing, researchers look for any signs of possible side effects that may have gone undetected in earlier patient research. Because of their large size, the studies are considered the most important study phase for picking up less common side effects and establishing safety.
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The trials also assess effectiveness by tracking who gets sick and who doesn't between patients getting the vaccine and those receiving a dummy shot.
Lasst week, AstraZeneca's US-traded shares fell more than 6 per cent in after-hours trading following reports of the trial being paused.
(With agency inputs)
