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Oxford publishes study confirms coronavirus vaccine is 70% effective and safe

Oxford University scientists today published a study proving that their coronavirus vaccine was safe and 70 per cent effective in clinical trials. 

And the UK’s regulator now faces a ‘dilemma’ over whether to approve a 1.5-dose regimen that appeared to boost it to 90 per cent after researchers discovered the improvement by accident.

The MHRA has been considering whether to approve the vaccine since November 27 and is expected to reach a decision before the end of the year.

AstraZeneca, the pharmaceutical company producing the vaccine, said the 62 per cent effectiveness seen in people who received two full doses of the jab was good enough to hit regulators’ standards around the world.

But a small group of volunteers who were mistakenly only given a half-dose first, followed by a full dose, were found to get a far better 90 per cent protection from the Covid-19.

Researchers on the project said the discovery was ‘intriguing’ and ‘unplanned’ but they had no idea whether the MHRA would want to approve it this way.

Professor Andrew Pollard, director of the Oxford Vaccine Group, said today: ‘Most of the data were generated to support the two full doses so I think that will be the focus of the regulatory review.

‘However, it is entirely up to the regulators to decide exactly what they think the label should say at the end.

‘It does complicate it – we didn’t set out with the expectation there would be differences between the groups.’

Scientists at the University of Oxford and British pharmaceutical company AstraZeneca have developed a coronavirus vaccine that a study shows is, on average, 70 per cent effective at preventing Covid-19

One expert said it was a 'dilemma' for regulators to decide how the vaccine should be given out, with a dosing regimen only tested on a small number of people appearing to be more effective (Pictured: A volunteer receives the Oxford jab in a trial in England)

One expert said it was a ‘dilemma’ for regulators to decide how the vaccine should be given out, with a dosing regimen only tested on a small number of people appearing to be more effective (Pictured: A volunteer receives the Oxford jab in a trial in England)

Dr Simon Clarke, a microbiologist at the University of Reading who was not involved with the development of the vaccine, said: ‘The report on the successful trial of the Oxford/AstraZeneca vaccine presents regulators with something of a dilemma. 

‘Data are most compelling for the cohort who got half a dose of the vaccine in their first jab. 

‘Not only does this seem to confer greater protection against disease, it is in this group that there is a reduction in asymptomatic transmission of the virus, something which is essential if herd immunity is to be obtained to get wider protection of the population. 

‘Unfortunately, this cohort was relatively small, reducing the reliability of the findings – moreover it did not contain any older participants (age 55 or over) and it remains possible that if the regulators allowed the vaccine to be used in this manner, the most at risk group may not be protected.’

The study published today in The Lancet confirms results that were announced by the scientists at the end of November.

Those were that, in a group of 5,807 people given the vaccine, only 30 tested positive for coronavirus, compared to 101 out of 5,829 people given a fake vaccine.

Overall the vaccine prevented 70.4 per cent of coronavirus cases among people who had it, the study said. 

More detailed data showed that three out of 1,367 people who were given half a dose followed by a full dose got the illness, which was 90 per cent prevention, compared to 71 out of 4,455 who got the normal two full doses (62 per cent). 

The 90 per cent protection would obviously be preferable for regulators but there is a lot less data to prove it works, meaning it is possible that the results were a fluke, and it was not tested on anyone over the age of 55.

The half-dose programme happened as a result of the wrong dose measurement being used and researchers didn’t realise until people had already had the jabs. 

When results were initially announced scientists raised concerns about the 90 per cent number, but the Oxford team explained today that they had already told drug regulators about the error and agreed to include it in their trial results for transparency a long time before it turned out to be more effective. 

Dr Pollard said: ‘I think it is fair to say it needs more looking into.

‘The use of the low dose was unplanned but we did discuss, before starting the phase three trial, the dosing with the regulators… 

‘They agreed that it was appropriate to continue the half-dose.’  

Margaret Keenan, a 90-year-old woman from Coventry, today became the first member of the public to get vaccinated against Covid-19 as the UK was the first in the world to start giving jabs to citizens

Margaret Keenan, a 90-year-old woman from Coventry, today became the first member of the public to get vaccinated against Covid-19 as the UK was the first in the world to start giving jabs to citizens

Today’s study also said researchers had found some evidence that their vaccine could prevent asymptomatic transmission of the virus, which is when people spread it to others without realising they are carrying it.

There is good evidence that existing Covid vaccines can prevent disease, but whether they can stop the virus spreading remains a big unknown.

Weekly swab-testing for participants in the British arm of the trial has suggested this jab may prevent that, the researchers said.

It could prevent 27 per cent of instances of this, they said, with 29 asymptomatic cases found in the vaccine group compared to 40 in the control group.

And again, the half-dose schedule seemed to give better protection, of up to 59 per cent.

Although these percentages seem low that is not the main point of the vaccine, which is intended simply to reduce the risk of serious illness and death. Any effect on transmission would be a bonus.

Better prevention of the virus spreading in the half-dose group was likely directly linked to the better effectiveness of the vaccine overall, the scientists said.

Professor Sarah Gilbert, one of the Oxford scientists who invented the vaccine said it was unlikely that the vaccine would give people complete protection against Covid-19 forever.

‘Sterilising immunity is probably not going to be very likely to happen over a long time, but that’s not what we need to control a pandemic,’ she said, adding that the researchers were confident it would lead to a decline in hospital admissions and deaths.

Professor Gilbert added: ‘We now have clear evidence of efficacy in the trial results presented in a peer-reviewed publication today. 

‘Now under regulatory review, we hope that this vaccine will shortly be in use to start saving lives.’ 

Independent scientists welcomed the study that today laid out all the data behind the Oxford-AstraZeneca vaccine, saying it showed that it was safe and effective.  

Dr Alexander Edwards, a biomedical technology expert at the University of Reading, said: ‘The vaccine is clearly safe, and has been into very large numbers of trial participants without any problems. 

‘It clearly provides protection that exceed expectations when the trials were planned.’


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