AstraZeneca to run new trial of Oxford Covid vaccine

Pharma giant will conduct extra tests after problems with dosage levels revealed

The drug company behind one of the UK's leading coronavirus vaccines is set to run an extra trial amid growing questions about the jab's performance.

On Monday, scientists from Oxford University and AstraZeneca revealed that their vaccine had achieved an overall efficacy rate of 70 per cent  in Phase Three trials. However, this rose to 90 per cent in a sub-group, a finding researchers said was "intriguing".

It was then revealed that this had stemmed from an error when some of those in the study were given just half a dose for the first jab when a full dose had been intended. Those given the intended dose saw efficacy rates of just 62 per cent.

The company has said it will run extra trials to satisfy regulators after US health officials revealed that nobody in the group with 90 per cent efficacy rates was above the age of 55.

The revelation sparked widespread concern because the jabs will be targeted at the elderly first. However, scientists in the UK pointed out that previous trials suggest the vaccines are highly effective in the elderly.

On Thursday night the UK Government instructed regulators to start their formal assessment of the jabs, with hopes that vaccination rollout could start next month. 

The UK has bought 100 million doses of the jabs, with hopes almost 20 million of them will be available by the end of the year. AstraZeneca insisted that the extra trial would not delay the process of authorisation in Britain, but scientists have urged those involved in the trial to provide more information about their findings.

The head of AstraZeneca has said the company would run an extra study in order to validate the findings in the sub-group. While the study of those given two full doses involved 8,895 people, the 90 per cent efficacy was based on a dosing regime given to just 2,741 people.

AstraZeneca chief executive officer Pascal Soriot said: "Now that we've found what looks like a better efficacy we have to validate this, so we need to do an additional study." He said he did not expect the additional trial to hold up regulatory approvals in the UK.

On Thursday night the Government confirmed that Professor Jonathan Van-Tam, deputy chief medical officer for England, has asked the Medicines and Healthcare products Regulatory Agency to begin formal processes to evaluate the safety and efficacy of the vaccine.

When the trial findings were revealed on Monday, neither AstraZeneca nor Oxford disclosed that the 90 per cent figure had been based only on a group of adults aged 55 and under. 

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Eleanor Riley, professor of immunology and infectious disease at the University of Edinburgh, called on the scientists to provide more information "clearly and completely", adding: "Trust is at a premium when it comes to vaccines and we must not  do anything that might in any way undermine that trust." 

Paul Hunter, professor of medicine at the University of East Anglia said: "Given that many vaccines are less effective in older people, we have to be even more cautious about taking this 90 per cent efficacy at face value, at least for older people."

Scientists from Oxford University said previous Phase Two trials had shown the vaccines were "very, very effective in the elderly", insisting that full data, which is about to be submitted to the Lancet medical journal, would reassure the public.

Sir John Bell, a Government adviser, said he could not imagine any reason why regulators would not accept the data once the full details were scrutinised.

A spokesman for AstraZeneca said: "Following established clinical trial standards, the data will be published in a peer-reviewed journal in due course."

Dr Charlie Weller, the head of vaccines at the research charity Wellcome, said: "It is important to take a step back and remember that these are interim results, so there are still many unanswered questions. Before drawing full conclusions, we must wait for the trial to finish and for the complete data to be independently and rigorously assessed."

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