Two major studies of vaccines against Covid-19, both paused because of potential safety concerns, are set to restart, the companies running them said Friday.
“The restart of clinical trials across the world is great news as it allows us to continue our efforts to develop this vaccine to help defeat this terrible pandemic,” Pascal Soriot, AstraZeneca’s CEO, said in a statement. “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.”
“We as a company have found no evidence the vaccine candidate caused the event, and we have agreed to restart the study,” Paul Stoffels, the chief scientific officer at Johnson & Johnson, said in an interview.
In both cases, new documents describing potential risks for both researchers and volunteers have been prepared, and must be approved by a centralized institutional review board, one of several groups charged with protecting patients in the trial.
AstraZeneca’s restart was first reported by the Wall Street Journal; the impending restart of the J&J study was first reported by the Washington Post.
AstraZeneca stopped administering new doses of its vaccine on Sept. 6, a step first reported by STAT, after a participant in the trial developed neurological symptoms. These symptoms were reportedly caused by transverse myelitis, a serious spinal cord condition.
AstraZeneca said in its statement that the voluntary pause was part of its standard review process for safety events, and that such pauses are not unusual. It said reviews from the trial’s independent monitoring committees indicated it was safe for the trials to resume, and that this conclusion was supported by international regulators.
A study of the vaccine in the U.K. restarted on Sept. 12, and shortly thereafter studies in Brazil and South Africa resumed. A study in Japan restarted earlier this month. But the Food and Drug Administration decided to further investigate the case, and the U.S. trial has remained on hold for more than a month.
A trial of another vaccine, being developed by Johnson & Johnson, was paused on Oct. 11. According to a person familiar with the matter, a male volunteer in his twenties had a cerebral hemorrhage and transverse sinus venous thrombosis. The Washington Post, citing two sources, said this case was a stroke.
Stoffels said that the case was reviewed by external experts, with reports made continuously both by the study’s data and safety monitoring board, an outside panel overseeing the studies, and the FDA. A final report was sent to the agency late this week. Circumstances with the patient made the process slower than it might have been.
“We worked as hard as we could,” Stoffels said. “We would not put more people at risk until we knew what the cause or relationship would be.”
The J&J study could begin enrolling patients again early next week, Stoffels said. He noted that the study already includes a large number of sites, and that the company will be making sure the participants are diverse in their ethnic background, their age, and any disorders they have that could make them higher risk.
The J&J effort is important because it is the only one of the major vaccine efforts to be testing a single dose, and the company has made the main goal of its study to test whether the vaccine prevents severe or moderate Covid-19, not just symptomatic cases of the disease.
Helen Branswell contributed reporting.