The world is waiting with bated breath for a coronavirus vaccine.
So when AstraZeneca, a frontrunner in Phase 3 of global trials, unexpectedly hit pause on its study due to a participant becoming ill, prospects for an early rollout dimmed.
While it might be disappointing, experts say it’s far from uncommon.
In fact, there’s some comfort to be found in the temporary hold, according to Craig Jenne, an associate professor in microbiology, immunology and infectious diseases at the University of Calgary.
“This is proof that the safety checks in place are robust and non-negotiable,” he said. “They didn’t wait for 10 patients to pause the study… We’re not willing to compromise safety to get a vaccine faster.”
AstraZeneca announced it would halt its trial Tuesday after a participant came down with a “potentially unexplained” illness. In a statement, the company said it would conduct an investigation and “review of safety data” to determine if the illness is a side effect of the vaccine or a coincidence.
The U.K.-based company began recruiting 30,000 people in the U.S. for its largest part of the study in late August. The vaccine is also being tested in thousands of people in Britain — as it’s being developed by Oxford University — as well as in Brazil and South Africa.
It’s been described by the World Health Organization as likely the world’s leading candidate and the most advanced in terms of development.
While the pause might be a setback, the researchers are ultimately being “very careful,” said Dr. Isaac Bogoch, an infectious disease specialist based out of Toronto General Hospital.
“This is exactly why you do Phase 3 clinical trials. You’re looking out for safety and efficacy,” he said. “There are certain things you can only find out if you give this drug or vaccine to thousands of thousands of people.”
‘Unexplained’ illness under review
AstraZeneca did not reveal any information about the possible side effect except to call it a “potentially unexplained illness.” However, a New York Times report citing an anonymous source “familiar with the situation” suggested that the participant in the U.K. trial was diagnosed with transverse myelitis — an inflammatory syndrome that affects the spinal cord and is often triggered by viral infections.
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Bogoch emphasized that this is “still speculation” since the investigation has not been completed in full. The timing of the diagnosis, and whether it is linked to the AstraZeneca vaccine, remains unknown.
“It might be real. It might not be real. Let’s just wait until we hear from the people actually following this closely.”
AstraZeneca did not elaborate on how it will conduct the investigation, nor the procedural methods it undertook in the process of the third-stage study.
Jenne suspects the researchers and doctors will go through a litany of potential interactions and potential causes of the reaction of the patient, “keeping in mind that this may still be completely coincidental.”
“What exactly was the response? Is it attributable to the vaccine formulation? Was it something to do with the administration of the vaccine? How was it administered? Who administered it? Was there an underlying medical condition?” he said.
Alasdair Munro, a clinical researcher of pediatric infectious diseases in Britain who is working on the Oxford vaccine trials, provided a snapshot of what that investigation might look like in a human vaccine trial.
Munro said on Twitter that participants in Oxford studies have 24-hour-a-day access to a study doctor and complete “symptom diaries” following the vaccination. The researchers are alerted “if any serious symptoms are recorded,” which are followed up on and reviewed to see if they are related to the vaccine.
“Everything gets recorded,” he wrote, from mild to serious, and the unrelated. “If they took paracetamol for a headache, it gets recorded. Antihistamine for sneezing, gets recorded.”
The moment there are concerns a serious symptom “could” be related, “the studies stop until their dedicated safety monitoring team can collect and review all the relevant information to ensure they are happy the study is safe to continue,” he wrote.
“These reviews are extremely rigorous.”
Other vaccines on the table
Depending on what’s determined, the trial could very well go back to a second stage or even have the third stage “retooled,” Jenne said.
All parties involved in the trials also have to come to a cohesive conclusion and agree on whether it’s safe to continue, he added.
One report from the Financial Times claims AstraZeneca’s trials may resume as early as next week.
“One thing Canadians have to remember is that not all vaccines are going to be approved. That’s the whole reason we have a Phase 3,” Jenne continued.
More than 150 potential vaccines are being developed and tested globally to stop the COVID-19 pandemic, with 34 in human trials.
“This is also why Canada has invested in four different vaccine platforms. In the case one isn’t approved for whatever reason, we’re not relying on that. We have backup plans.”
Bogoch took it one step further. As pressure on researchers and pharmaceutical companies has grown, so, too, have concerns about fast-tracking trials.
The WHO has warned that “if you move too quickly to vaccinate… millions of people, you may miss certain adverse effects.”
“We hear these narratives. ‘We can’t rush this process,’ and ‘Is it going to be safe?'” Bogoch said.
“Well, here’s your safety mechanisms at work.”
— with files from the Associated Press and Reuters
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