AstraZeneca said on Sept. 9 that there is “no final diagnosis” for the single COVID-19 vaccine trial participant who has developed a “potentially unexplained” illness, causing the company to temporarily halt for the second time its late-stage Phase Three trial for its vaccine candidate.
A spokesperson for the company said in a statement Wednesday that reports claiming to be made by AstraZeneca’s CEO, Pascal Soriot, saying that he confirmed the participant presented adverse symptoms are “incorrect.”
“Reports claiming to be based on comments made earlier today by our CEO stating that we have confirmed that a participant in our clinical trial suffered from transverse myelitis are incorrect,” the spokesperson said. “He stated that there is no final diagnosis and that there will not be one until more tests are carried out.”
Soriot had said during a private conference call with investors on Wednesday morning that one trial participant was experiencing undiagnosed neurological symptoms, which were said to be consistent with a rare but serious spinal inflammatory disorder known as transverse myelitis. It link between the symptoms and the vaccine are unclear.
The spokesperson said that tests from the ill patient will be sent to be reviewed by an independent safety committee to establish a final diagnosis. It is not clear how long the clinical trial will be paused for.
AstraZeneca also confirmed that this is the second time the COVID-19 vaccine trial has been temporarily halted over safety concerns in recent months. A review found that a previous case of illness was not related to the vaccine.
“There was a brief trial pause in July while a safety review took place after one volunteer was confirmed to have an undiagnosed case of multiple sclerosis, which the independent panel concluded was unrelated to the vaccine,” the spokesperson said.
The announcement comes after the company said on the evening of Sept. 8 that its “standard review process triggered a pause to vaccination to allow review of safety data,” without elaborating. At the time, health news site STAT reported that the pause was prompted by a potential side effect for a patient in the United Kingdom.
The pause applies to all the trial studies AstraZeneca is running in the United States and other countries. The company began recruiting 30,000 participants in the United States in August. Thousands of people in Britain, Brazil, and South Africa are also part of the trial.
Moderna and Pfizer are also conducting large-scale final-stages trials in the United States for vaccines that work differently from AstraZeneca’s. Moderna and Pfizer have recruited roughly two-thirds of the needed participants.
The World Health Organization’s chief scientist, Dr. Soumya Swaminathan, said the U.N. health agency is currently not too concerned about the pause. The scientist described it as “a wake-up call” to the global community about the inevitable ups and downs of medical research.
AstraZeneca boss Soriot said Thursday that, should the vaccine trials safely resume, it should still be feasible to make its COVID-19 vaccine available by the end of the year.
Soriot said that if the independent review allows global trials to restart, the company remains on track for submitting data to the regulator by year end.
“Then, of course, it depends on how fast the regulator will review and give approval, so we could still have a vaccine by the end of this year or maybe early next year,” he said during an event held by Tortoise Media.
He noted that it is normal for vaccine trials to be halted and restarted to conduct safety reviews.
“The difference with other vaccine trials is the world is not watching them, of course. They stop, they study, and they restart.”
Ivan Pentchoukov contributed to this report.