A woman who received an experimental coronavirus vaccine developed severe neurological symptoms that led to a pause in testing, a spokesman for the pharmaceutical AstraZeneca said on Thursday.
The study participant in the late-stage trials reported symptoms consistent with transverse myelitis, a rare inflammation of the spinal cord, company spokesman Matthew Kent said.
“We don’t know if it’s (transverse myelitis),” Kent said. “Now more tests are being done as part of the follow-up.” On Tuesday, AstraZeneca said its “standard review process caused a pause in vaccination to allow for review of safety data.”
He did not provide more details than saying that only one participant had an “unexplained illness.” The vaccine was initially developed by the University of Oxford after the coronavirus pandemic began this year.
Kent said an independent committee was reviewing the study’s safety data before deciding if and when the research could continue.
The study was previously stopped in July for several days after a participant who received the vaccine developed neurological symptoms; it turned out to be an undiagnosed case of multiple sclerosis that was not related to the vaccine.
Late last month, AstraZeneca began recruiting 30,000 people in the US for its largest study of the vaccine. She is also testing the vaccine in thousands of people in Britain and in smaller studies in Brazil and South Africa. Several other Covid-19 candidate vaccines are in development.
Dr Soumya Swaminathan, chief scientist at the World Health Organization, said the UN health agency was not overly concerned about the pause in the Oxford and AstraZeneca vaccine trial, describing it as “a wake-up call” to the world community about the inevitable ups and downs of medical research.
Temporary holds from large medical studies are not unusual, and the investigation of any serious or unexpected reactions is a mandatory part of safety testing.
AstraZeneca noted that the problem may be a coincidence; diseases of all kinds could arise in studies of thousands of people.
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