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The Oxford University AstraZeneca Covid-19 vaccine trial has been paused – should we be worried?
The halt in development of the University of Oxford’s Covid-19 vaccine due to an adverse reaction in a trial participant has triggered fears of a delay in finding a solution to coronavirus restrictions.
A spokesman for AstraZeneca, the company working with the academic team to produce the vaccine, said the voluntary pause is “routine”.
While governments around the world have backed this specific vaccine, details of the “potentially unexplained illness” in one of the trial’s participants are unclear.
Here’s what we know, and what it could mean for the Covid-19 vaccine race.
What has happened to the Oxford University vaccine trial?
On Tuesday the British-Swedish pharmaceutical company AstraZeneca confirmed that one of the volunteers in a UK trial of the vaccine had developed an unexplained illness.
The company said it took the step to halt the trial voluntarily.
All trials of this vaccine, which have so far included at least 17,000 people across the UK, Brazil and South Africa, have been halted.
The vaccine had previously generated strong immune responses, and is currently in phase three trials – the final step before a vaccine is approved.
Details of the unexplained illness have not been released, but according to a New York Times report one volunteer in the UK program had received a diagnosis of transverse myelitis – an inflammation across the spinal cord. However, AstraZeneca has not commented on this, and there is no evidence the patients with transverse myelitis includes the patient who triggered the study halt. The report was careful to note that the timing of the diagnosis, and whether it was directly linked to AstraZeneca’s vaccine, was still unknown.
What will this mean for the vaccine? How long will it be paused for?
While all trials are paused, an independent committee will review the safety data of the virus to determine whether the illness reported in the trial participant can be attributed to the vaccine, or whether it was an unrelated illness they developed.
Prof Robert Booy, a University of Sydney professor of vaccinology, told the Guardian the investigation of the sickness, if it proves to be isolated and unrelated to the vaccine, could mean the vaccine’s trials are halted for as little as one week and as long as one month.
Booy believes the halt “is more likely the product of being super careful” as opposed to being a problem with the vaccine.
Is this common? Have vaccine trials been paused before but later approved?
Yes, according to AstraZeneca, who have called this a “routine action”.
The BBC reported this is the second time this particular vaccine has been paused since trials began in April.
More generally, medical experts also say pausing trials is common, with Booy believing the pause is actually a “promising” sign of rigour in the development process.
He said this particular incident has only been widely reported because “the world’s eyes are on this vaccine”, and that the trial halt was more likely the product of being super careful”.
“This could have just been a high fever and it turns out they’ve got appendicitis,” he said. “My bet would be that they find something in this participant that is not causal [from the vaccine]. It’ll take them about one to two weeks to ascertain this, and then they will probably restart the trial in a month.”
What if the review determines this is an unrelated illness?
The trials will resume. Booy believes this will be the most likely outcome and thinks the vaccine can still be delivered by the beginning of 2021.
What if the review finds the patient’s illness was caused by the vaccine?
If further incidents of the adverse reaction are discovered in other trial participants, or if the reaction is proved to have been caused by the vaccine, the vaccine is unlikely to be the first to be rolled out.
Is this vaccine our only hope?
No. The Oxford vaccine is one of six vaccines in phase-three trials (the final step before approval) around the world.
While the UK and Australian governments have committed to 100m and 33.8m doses of the vaccine respectively, there are several other options.
The UK government has also signed a deal for 90m doses for another vaccine, developed between BioNTech, Pfizer and Valneva.
The Australian government on Monday, when announcing its deal for the Oxford vaccine, also included a deal with company CSL for 51m doses of a University of Queensland vaccine, currently in pre-clinical trials.
Earlier on Tuesday, the CEOs of nine companies developing different vaccines, including AstraZeneca, as well as BioNTech, GlaxoSmithKline, Johnson & Johnson, Merck, Moderna, Novavax, Pfizer and Sanofi, pledged to make a “united commitment to uphold the integrity of the scientific process as they work towards potential global regulatory filings and approvals of the first Covid-19 vaccines”.
Booy noted the Oxford vaccine uses a modified chimpanzee adenovirus, while other vaccines being trialled rely on different proteins.
He noted the vaccine from US company Moderna, which relies on mRNA, was also in phase three of trials, and another promising option.
How likely is a vaccine now?
Booy believes the Oxford vaccine should not be written off based on this one patient’s reaction.
He said that if the illness is linked to the vaccine, he is still optimistic one of the six vaccines currently in phase three will be approved and rolled out by the beginning of next year.
“We’ve never had as many clever people working in as great a number as we have had on these vaccines.”
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