AstraZeneca and Johnson & Johnson have separately announced that they are restarting U.S. clinical trials on their respective coronavirus vaccine candidates, after both companies had paused the trials due to potential safety issues.
AstraZeneca resumes US clinical trial on experimental coronavirus vaccine
On Sept. 6, AstraZeneca announced that it had paused all of the company's Phase 3 clinical trials for its coronavirus vaccine candidate to investigate a serious illness that had developed in a trial participant in the United Kingdom. At the time, AstraZeneca explained that participants in large clinical trials can sometimes become sick by chance, and not necessarily because of the experimental treatment they received, so unexpected illnesses "must be independently reviewed to check this carefully." As such, the company said the pause in Phase 3 trials was 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."
The company at the time did not provide extensive details on the participant's illness. However, a source had told the New York Times that a participant in the United Kingdom, who had been enrolled in a Phase 2/3 trial, was diagnosed with transverse myelitis, which is an inflammatory syndrome that affects the spinal cord and is often triggered by viral infections.
During AstraZeneca's pause of its trials, an independent safety board reviewed the incident and determined the participant's illness was unrelated to AstraZeneca's coronavirus vaccine candidate. Based on that review board's findings, AstraZeneca earlier this month was permitted to resume its trials in most countries, but not in the United States. According to two vaccine experts familiar with the matter who spoke to the Times on a condition of anonymity, FDA at that point had not been able to directly connect the experimental vaccine to the participant's illness, but the agency also couldn't rule out a connection.
However, federal regulators have since determined that there's no evidence that AstraZeneca's coronavirus vaccine candidate was connected to the participant's illness, and FDA on Friday authorized AstraZeneca to resume its U.S. trials on the experimental vaccine. In a statement, AstraZeneca said, "FDA reviewed all safety data from trials globally and concluded it was safe to resume the trial."
Pascal Soriot, CEO of AstraZeneca, in the statement said, "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." He added, "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."
J&J to resume trials on its coronavirus vaccine candidate
Separately, J&J on Oct. 12 announced that it, too, had paused all of its clinical trials on its experimental coronavirus vaccine to investigate an "unexplained illness in a study participant."
J&J hasn't provided additional information about the illness or the affected participant. The company in a statement first issued Oct. 12 said, "We must respect this participant's privacy. We're also learning more about this participant's illness, and it's important to have all the facts before we share additional information."
However, a person familiar with the matter told STAT News that the volunteer had developed a cerebral hemorrhage and transverse sinus venous thrombosis, and two sources told the Washington Post that the participant had a stroke.
In an update posted to its earlier statement on Friday, J&J said the "serious medical event" the participant experienced had "no clear cause."
"There are many possible factors that could have caused the event," J&J said, but "[b]ased on the information gathered to date and the input of independent experts, the company has found no evidence that the vaccine candidate caused the event."
In light of that determination, J&J announced that the company would soon resume its trials on its coronavirus vaccine candidate. "The independent Data Safety and Monitoring Board … overseeing the [clinical trial] has recommended resuming trial recruitment," J&J said. "Following consultation with [FDA], preparations to resume the trial in the United States, including submissions for approval by the Institutional Review Boards, are now underway."
Paul Stoffels, J&J's chief science officer, said the trial's delay won't significantly alter the company's timeline for developing its vaccine. "We have the ability to catch up," he said, "[b]ut if there is a delay, it's in the one or two week time frame" (Wu et al., New York Times, 10/23; Burton/Loftus, Wall Street Journal, 10/23; Johnson, Washington Post, 10/24; Herper, STAT News, 10/23).