AstraZeneca and Johnson & Johnson announced Friday that they would resume their phase 3 clinical trials on Covid-19 vaccine candidates in the United States.
AstraZeneca’s trial was put on hold just days after it began in early September, following news of a British participant who developed a spinal cord injury after receiving the experimental vaccine. Johnson & Johnson’s trial was paused on Oct. 12 after an unspecified injury in one of its study participants.
"We're very optimistic about both AstraZeneca and Johnson & Johnson resuming their trials just as quickly as possible," Paul Mango, deputy chief of staff for policy at the U.S. Department of Health and Human Services, said on a media call Friday.
The drugmakers rejoin Moderna and Pfizer in late-stage clinical trials in the U.S. Those companies have announced that they intend to submit applications for emergency use authorization in the second half of November, Mango said. On Thursday, Moderna said it had completed enrollment for its 30,000-person trial.
In a statement Friday, Johnson & Johnson said it found no evidence that the vaccine candidate caused the undisclosed injury. It is not clear whether the volunteer received the experimental vaccine or the placebo.
Dr. Matt Hepburn, vaccine lead for Operation Warp Speed, said on the media call that the trial holds should reassure Americans that the highest standards are being followed.
"This is how to keep a clinical trial running at the highest ethical and quality standards," Hepburn said of the AstraZeneca trial.
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The Operation Warp Speed briefing comes on the heels of a Thursday meeting of the Food and Drug Administration’s vaccine advisory committee, which met for the first time to discuss Covid-19 vaccines. At the all-day meeting, independent experts raised concerns about the vaccine trials, questioning whether they were designed to pick up on safety issues. Another common question was whether granting an emergency use authorization would hinder long-term safety studies.
Mango predicted vaccines will be available for the "most vulnerable citizens" by the end of 2020, with all seniors able to get a vaccine by the end of January.
He added that by April, the nation will "be able to vaccinate any American."