Explained: What Oxford-AstraZeneca Covid-19 vaccine trial pause means for trials

Why have the Oxford-AstraZeneca candidate vaccine trials been halted?

Though AstraZeneca did not specify what exactly had happened, it has been reported that a trial participant in England developed “serious adverse” illnesses. As of now, it is not even clear whether the “adverse event” is even a result of the vaccine. The pause will enable the company to review what was the cause.

What does it mean for the trials now?

This is a temporary pause, to investigate the illness in the affected patient, though it is not clear how long that is going to take. As of now, there do not appear to be any serious question marks over the safety of the vaccine, because such incidents are not uncommon in trials for vaccines or drugs. The only direct impact of the incident could be on the timeline for producing the vaccine. AstraZeneca, like other developers, has been targeting early next year for making its vaccine available.

But the incident has implications beyond that, for other vaccine developers as well. It demonstrates the inherent uncertainties in the process of developing a vaccine, and the importance of rigorously following the scientific method during trials.

What are these larger implications?

In the current rush to produce a coronavirus vaccine as early as possible, several usual regulatory procedures have been bypassed, raising concerns amongst experts and scientists. By all accounts, a coronavirus vaccine is expected to be ready by early next year. That itself would have made it the fastest developed vaccine, ever.

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FILE — Blood samples taken from a volunteer during a vaccine trial at Churchill Hospital in Oxford, England, Aug. 24, 2017. COVID-19 risk doesn’t depend on blood type, new studies reveal. (Andrew Testa/The New York Times)

But now, there is also an attempt, especially in the US, to release the vaccine this year itself. There is also a political push make the vaccine, at least notionally, available before the November 3 Presidential elections. President Donald Trump, seeking a re-election, has repeatedly said that a vaccine could be available this year, possibly before November 3. The vaccine is seen as boosting his re-election chances.

Elsewhere as well, there has been a rush to come out with a coronavirus vaccine, even if that means skipping phase-3 trials. The Russian vaccine, and a couple of candidates in China, have been approved in their respective countries without phase-3 trials having been initiated. It is only now, after much criticism, that these vaccines are also preparing to undergo phase-3 trials.

Are such incidents unusual during trials?

Shahid Jameel, a virologist, said the incident only highlighted the importance of following the prescribed processes. “The incident itself is nothing to be alarmed about as of now. These things happen quite routinely during vaccine or drug trials. The good thing is that despite the rush to produce a coronavirus vaccine, we still have systems in place that would pick these things out. So that is reassuring,” he said.

Unlike phase-1 and phase-2 trials, where the volunteers are carefully chosen to be healthy adults, phase-3 trials involve a very large number of participants, some of whom can have underlying diseases or weaknesses. As a result, it is not unusual for a case like the current one to emerge during the trials.

“When such things emerge, and they do quite regularly, you have to pause, reassess, re-examine. And that is what seems to be happening in this case. This is normal process, and this is how it should be,” Jameel said. The incident is a reminder against deviating from prescribed processes in developers’ keenness to fast-track their development. It will also likely temper public expectation and excitement about a vaccine being made available very soon, and possibly ward off political pressure to rush through the process to meet political deadlines.

Also read | At what stage are under-trial Covid-19 vaccine candidates in India? A recap of the major players

A employee is seen at the Reference Center for Special Immunobiologicals (CRIE) of the Federal University of Sao Paulo (Unifesp) where the trials of the Oxford/AstraZeneca coronavirus vaccine are conducted, in Sao Paulo, Brazil, June 24, 2020. (Reuters Photo: Amanda Perobelli)

A day earlier, nine pharma companies, including AstraZeneca, had released a joint statement promising not to prematurely release their vaccines, and “always make the safety and well-being of the vaccinated individuals” their top priority. These companies said they would seek approval for their vaccine candidates only “after demonstrating safety and efficacy through a phase-3 clinical study”.

Will the incident impact the India trials?

AstraZeneca has not explicitly clarified whether trials at all locations have been paused. As such, the status of the India trials, being sponsored by Pune-based Serum Institute of India, is not clear. Serum Institute itself said the incident will have no impact on the ongoing trials here, and that it had faced “no issues at all” in the trials so far.

But the trials in India are already in a temporary, scheduled, pause, unrelated to the incident, right now. In the initial round of the trials, 100 participants have been vaccinated. Follow-up information from these participants is to be submitted to an independent expert body, called the Data Safety and Monitoring Board (DSMB), for review. Only after the expert body has reviewed and approved the data will the trials sites go ahead vaccinating more volunteers. Further enrolment of participants in India has been put on hold for the last one week, when the first 100 volunteers had been vaccinated.

In this handout photo released by the University of Oxford a doctor takes blood samples for use in a coronavirus vaccine trial in Oxford, England (AP Photo/File)

What will the Board look at?

The DSMB is expected to meet on Thursday or Friday to assess the data generated from the first group of volunteers. It will then decide whether the vaccine candidate is safe enough to be administered in more participants. If it finds any serious safety issue, it can even recommend that the trials be stopped. Some of the principal investigators involved in the trials expect the DSMB to now also take up this new incident when it conducts its own review. “The DSMB will review the Indian data along with this particular event (in the UK participant) that has occurred, and then decide and let us know what has to be done,” one of the investigators said.