Johnson & Johnson has paused its clinical trials for a Covid-19 vaccine candidate after a participant fell ill, just weeks after it announced that trials were in their final stage.
A pause is not entirely unexpected in vaccine trials. When another vaccine trial was temporarily stopped last month, experts hailed the move as an example of the scientific rigor that is being maintained despite the understandably intense public interest in a Covid-19 vaccine.
The Johnson & Johnson trial was paused in compliance with regulatory standards after one of its participants developed an "unexplained" illness, the company said in a news release Monday night. It said the participant's condition was being reviewed and evaluated by the ENSEMBLE independent Data Safety Monitoring Board.
"We must respect this participant's privacy," the company's statement said. "We're also learning more about this participant's illness, and it's important to have all the facts before we share additional information."
It is unclear whether the participant received the experimental vaccine or was in the placebo control group.
AstraZeneca also started its phase 3 trial of a vaccine candidate last month, but it was placed on pause in the U.S. after a participant in the United Kingdom was reported to have developed a spinal cord injury. The company resumed its trial with the University of Oxford in the U.K. but was awaiting approval from the Food and Drug Administration to continue in the U.S.
Dr. Francis Collins, director of the National Institutes of Health, said last month that the pause should reassure those with concerns about possible safety issues.
"If anybody thinks we're just glossing over these kinds of issues in the big rush to approve a vaccine, this ought to be reassuring," Collins said during a "Doc to Doc" interview with NBC News medical correspondent Dr. John Torres, which was streamed on Facebook.
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Pfizer and Moderna also have vaccine candidate trials that went into phase 3 in July, both of which require two doses about a month apart. The Johnson & Johnson vaccine candidate is instead administered in one dose, avoiding the complicated coordination to require people to return in time for the second dose.
Johnson & Johnson announced last week that the European Commission had approved an advance purchase agreement from Janssen Pharmaceutical Companies, a subsidiary of Johnson & Johnson, for 200 million doses of the vaccine for E.U. member states following approval. The company also said it was looking to allocate up to 500 million vaccine doses to international efforts for low-income nations.
CORRECTION (Oct. 13, 2020, 11:20 a.m.): An earlier version of this article misstated Janssen Pharmaceutical Companies’ relationship with Johnson & Johnson. It is a subsidiary, not its parent company.