Oxford Vaccine Trials to Resume In UK, Were Paused Over Volunteer's Illness

 Study restarts after halt to assess participant’s illness.No word from Astra or Oxford on status of separate U.S. trial.

The University of Oxford and AstraZeneca Plc have restarted a U.K. trial of an experimental Covid-19 vaccine after it had been halted over concerns about a participant who fell ill.

The U.K. Medicines Health regulatory authority recommended that the study resume after an independent review of the safety data triggered an interruption on Sept. 6, Oxford said in a statement. It declined to disclose details about the volunteer’s illness.

While temporary halts are common in vaccine trials, the interruption to the closely watched Astra-Oxford study had raised concerns about the viability of one of the fastest-moving experimental shots seeking protection from the pandemic. The race to develop a Covid-19 vaccine has compressed what's normally a decade-long process into a matter of months, with data from final-stage trials expected as soon as next month.

Statements from Astra and Oxford on Saturday didn’t say anything about the status of tests outside the U.K. Trials of the Oxford vaccine were underway within the U.S., Brazil, South Africa and India before being paused after the safety review.

A representative for the U.S. National Institutes of Health couldn’t immediately be reached for comment. An AstraZeneca spokesman declined to comment.

Suspected Diagnosis

AstraZeneca Chief executive officer Pascal Soriot said on Thursday that the vaccine could still be available by the end of the year. An independent safety board was reviewing whether the participant’s illness had been caused by the vaccine or was unrelated, he said.

Soriot said it wasn’t clear whether the participant had a condition called transverse myelitis, a suspected diagnosis. NIH Director Francis Collins told a Senate committee Wednesday the trial had been halted due to a “spinal cord problem.”

“We cannot disclose medical information about the illness for reasons of participant confidentiality,” Oxford said. “We are committed to the safety of our participants and the highest standards of conduct in our studies and will continue to monitor safety closely.”

Oxford said some 18,000 people have received “study vaccines” as a part of the trials. It had begun a large phase 3 trial within the U.S. at the end of August, with the aim of enrolling 30,000 people.

AstraZeneca is one among several companies participating within the U.S. government’s Operation Warp Speed program to fast-track a coronavirus vaccine. In May, the company inked a $1.2 billion deal with the U.S. to support clinical studies and provide 300 million doses of the vaccine. it's pledged to provide the vaccine on a not-for-profit basis during the pandemic and has lined up deals round the world to supply almost 3 billion doses.

Human Trials

Oxford began human trials of its shot on April 23 in almost 1,100 volunteers and at the end of May advanced quickly to a large-scale study within the U.K. involving more than 10,000 people including those over the age of 55. Researchers are looking for a significantly higher number of Covid-19 cases within the control group over the vaccinated group to show the shot is effective.

The trial started even as rates of infection within the U.K. began dropping in May, making it harder to demonstrate whether the vaccine works. In recent weeks, new cases are climbing again.

In July, Oxford reported initial results showing the vaccine increased levels of protective neutralizing antibodies and immune T-cells that target and destroy infected cells. It didn’t report any serious adverse events as a part of its phase 1-2 trial. Researchers pressed ahead with trialing a two-dose regime after finding it produced a stronger response in 10 volunteers. It’s unclear whether the participant who fell ill had two doses or one.

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