Results from trials of jab ‘imminent’ as hopes raised by early data on versions from Moderna and Pfizer
Results from trials of jab ‘imminent’ as hopes raised by early data on versions from Moderna and Pfizer
Following a series of recent steps forward in the race to develop an effective Covid-19 vaccine, attention is turning to the much-anticipated results from trials of Oxford University’s candidate.
The UK has so far purchased 40 million doses of the vaccine developed by US pharmaceuticals giant Pfizer, and has also rushed to reserve five million of Massachusetts-based Moderna’s candidate, after both were found in late-stage trials to have an efficacy of more than 90%. But “Britain has the most riding on the inoculation being developed by Oxford University and AstraZeneca – of which it has reserved 100 million doses”, The Guardian reports.
A source at the Department of Health and Social Care told the newspaper that the first results from the Oxford trials are “imminent” and that provided approval is granted by regulators, the jab could be one of the first of the 200-odd being developed worldwide to be rolled out.
At what stage of development is the Oxford vaccine?
The Oxford University vaccine, made in partnership with Cambridge-based company AstraZeneca, has long been a front runner in the contest to find a coronavirus jab.
In early September, trials of the vaccine resumed after being briefly paused as a result of a reported side effect in a patient in the UK. The jab is currently in Phase 3 testing that has involved “some 30,000 participants in the US as well as in the UK, Brazil and South Africa”, the BBC reports.
Although Phase 3 trials can take several years, Politico London Playbook’s Alex Wickham confirms that “government officials expect positive news soon and for it to be ready for rollout alongside the Pfizer jab in December”.
How does the jab differ from the other candidates?
While the Oxford vaccine – called ChAdOx1 nCoV-19 – “uses a different technology from the Moderna jab, the two vaccines both rely on stimulating cells to produce a specific protein, which in turn triggers an immune response – meaning Moderna’s results bode well for Oxford”, The Guardian reports.
But unlike the Oxford jab, those developed by Modena and Pfzier use messenger ribonucleic acid, also known as messenger RNA, or mRNA.
Conventional vaccines are produced using weakened forms of a virus, but mRNAs use only the genetic code of the virus. In the Covid vaccines, the mRNA carries instructions for making the spike protein that protrudes from the outside of the coronavirus cell.
Once injected, the vaccine causes “protein-making machinery within the human cells to churn out this spike protein”, prompting the immune system to go into defence mode, the paper explains.
By contrast, the Oxford version is a conventional vaccine, using a harmless, weakened version of a common virus that causes colds in chimpanzees. Researchers have previously used this technology to produce vaccines against pathogens including flu, Zika and Middle East Respiratory Syndrome (Mers).
And the Oxford team are now using the “harmless chimp cold virus to deliver genetic information from the coronavirus to human cells to trigger the production of the spike protein” that kick-starts the immune response, says The Guardian.
So will it end the pandemic?
Professor Andrew Pollard, director of the Oxford Vaccine Group, told The Guardian that “the positive results from the other developers means it is likely that there will be multiple vaccines on target, which is great news for the world”.
But concerns persist over how long the vaccine protection will last.
Since the Oxford jab “uses a live chimpanzee adenovirus to transport elements of Sars-Cov-2 into humans, it’s expected people will develop immunity to the viral vector, preventing the vaccine from being used for future top-ups”, The Independent reports.
“For a scenario where the Oxford vaccine gets rolled out across the UK, that might give people protection for six months to a year,” Professor Robin Shattock, who is leading a separate team of vaccine researchers at Imperial College London, told the paper. “But you then need something to come back and reboost people.”
Shattock believes that his vaccine could be used as a regular booster for maintaining immunity. And that could offer “a permanent route out of the pandemic”, The Independent suggests.
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