Only ‘small chance’ of distributing the AZD1222 vaccine in the UK before Christmas

By Jane Byrne

- Last updated on GMT

© GettyImages/Manjurul
© GettyImages/Manjurul

Related tags Vaccine COVID-19 Clinical trial

Late-stage trial results on AstraZeneca’s COVID-19 vaccine could be ready by December.

"I'm optimistic that we could reach that point before the end of this year,"​ said Professor Andrew Pollard, chief investigator of the Oxford Vaccine Trial.

He was giving evidence to MPs at a joint hearing of the science and health committees​ of the UK’s House of Commons.

But the lead on the Oxford University group developing the AZD1222 vaccine was not overly optimistic on the odds of it being deployed in the UK by Christmas. He only sees a “small chance”​ of that happening.

The Oxford team, working with pharmaceutical firm AstraZeneca, has yet to carry out analysis of the clinical trials to see if the vaccine actually works.

Furthermore, if the data are positive, they then have to go undergo review by policymakers.

“All of the data needs to be put together and then presented to regulators, both in the UK and other countries around the world.

“We absolutely need that to happen so there’s very careful scrutiny of everything that’s been done in the clinical trials, to look at their integrity and the quality of the data and to verify that the results are correct,”​ said Pollard.

Following that step, policy decisions would be required as to which groups should be entitled to get the AZD122 vaccine first and how might it be deployed.

Pollard said the timelines linked to all of those steps are not overly clear to him right now.

“Our trials are only one of many that are happening all over the world, a number of which might well report before the end of the year. And those steps would need to be happening for multiple different products."

The more positive outcomes the better as a significant vaccine supply is required for global distribution: “I certainly hope we have lots of successes with the different platform technologies that are being used."

Efficacy question 

The degree of efficacy of a vaccine plays a part in its rollout as well.  

The US regulator, the Food and Drug Administration (FDA), has set the bar at the level of at least 50% efficacy to approve a vaccine.

However, to be able to scientifically test 50% is hard work, and it would also result in a delay in the timing of trial data release, as, under such efficacy parameters, more participants in the trial would need to develop COVID-19 to show it works, he explained. 

“So we are all hoping that vaccines would be more effective than that, [as that would mean] we would have an answer sooner.”

But if a vaccine was identified as having only 40% efficacy, policymakers would have to consider whether it would be of help, said Pollard.

“If vaccines only prevented 40% of the cases, would that be useful for the NHS? These are the sorts of decisions that potentially policy makers may need to be thinking through in the months ahead depending on where vaccines land.”

AZD1222 was co-invented by the University of Oxford and its spin-out company, Vaccitech.

It uses a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein. 

On Sunday [November 1], AstraZeneca confirmed the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) had started an accelerated or rolling review of AZD1222. Regulators are able to review data in real time under a rolling review process, which is designed to help speed up the approval timeline of potential vaccines for the novel coronavirus. 

Timelines revealed on Imperial vaccine 

Robin Shattock, chair in mucosal infection and immunity at Imperial College London, also gave evidence on the development of the self-amplifying RNA (saRNA) COVID-19 vaccine trial he is leading.

“Our timelines our slightly longer than the Oxford vaccines as we are developing completely new technology that has never been in clinical trial before but, with the right level of support, we could deliver an efficacy signal mid-way through next year with regulatory approval following closely after that.”

One of the advantages of the technology they are developing, he said, is that it can be used for repeated immunization boosting.

The Imperial vaccine is based on a new approach that uses synthetic strands of genetic code (called RNA), based on the virus’s genetic material. Once injected into muscle, the RNA self amplifies – generating copies of itself – and instructs the body’s own cells to make copies of a spiky protein found on the outside of the virus. This should train the immune system to respond to the coronavirus so the body can easily recognize it and defend itself against COVID-19.

The question as to whether these vaccines should be rolled out widely in the UK population depends on having the data indicating that they prevent disease or they block transmission - that is a critical determinant in their deployment, said the experts.

If it turns out the data shows the vaccines only prevent disease but do not impact on transmission it makes sense then that they should be deployed in vulnerable sections of the population, especially given the likely restraints in supply initially, they added.

Related topics Markets & Regulations COVID-19

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