Several individuals familiar with the event, who spoke on the condition of anonymity, said that an individual in Britain who was enrolled in a Phase 2/3 trial had experienced symptoms consistent with a condition called transverse myelitis, or inflammation of the spinal cord.
The trial’s suspension will allow an independent board of experts to determine whether the participant’s condition was linked to the vaccine or merely coincidental, said Saad Omer, a vaccine expert at Yale University.
Part of this process will include generating a timeline of the participant’s symptoms to see if they match up roughly with when the vaccine was administered. The committee will also investigate other potential causes of the symptoms, in a process of elimination. After determining whether AstraZeneca’s vaccine is a probable culprit, experts will advise the company on whether to resume their trials.
In the interim, no further doses of the vaccine will be administered. It remains unclear how long the evaluation process will take. AstraZeneca representatives did not respond to repeated requests for comment and clarification.
The suspension is the second time that AstraZeneca has halted coronavirus vaccine administration in Britain because of severe neurological symptoms, according to information sheets uploaded to a clinical trial registry that was first reported by Nature News. Another participant developed symptoms of transverse myelitis, researchers reported in July, and was later diagnosed with an “unrelated neurological illness.” After a safety review, trials resumed.
Transverse myelitis is relatively rare, prompting symptoms in roughly 1,400 people each year in the United States, according to the National Institutes of Health. Its root cause is often mysterious, although doctors believe that the syndrome generally results when inflammatory responses in the body go awry, sometimes in response to an ongoing or past infection, said Dr. Felicia Chow, a neurologist at the University of California, San Francisco. “It’s not uncommon that we never figure out the cause,” Dr. Chow said.
There has been some past speculation that vaccines might be able to cause transverse myelitis, she added, but “there’s never been really any clear-cut, definitive proof.”
Source : https://www.nytimes.com/2020/09/09/world/covid-coronavirus.html