Video report by ITV News Science Editor Tom Clarke
The Oxford University and AstraZeneca Covid-19 vaccine - of which the UK has ordered 100 million doses - can prevent up to 90% of people contracting coronavirus and getting seriously ill, with some indications that it can also prevent people passing the virus to others.It is anticipated that 19 million doses will be available in the UK before the end of the year, if it is approved by the regulatory body, with each vaccinated person requiring two doses.
Scientists working on the jab found that when half a dose is given, followed by a further full dose, the vaccine was 90% effective.
However, when two full doses were given, the figure was only 62%.
The combined analysis from both dosing regimes resulted in an average efficacy of 70.4%, due to more people being trialled on two full doses.
Sarah Gilbert, professor of vaccinology at the University of Oxford explains how the dosages work
In a statement, Professor Andrew Pollard, director of the Oxford Vaccine Group and chief investigator of the Oxford Vaccine Trial, said: “These findings show that we have an effective vaccine that will save many lives. Excitingly, we’ve found that one of our dosing regimens may be around 90% effective and if this dosing regime is used, more people could be vaccinated with planned vaccine supply.
“Today’s announcement is only possible thanks to the many volunteers in our trial, and the hard working and talented team of researchers based around the world.”
Prime Minister Boris Johnson hailed the breakthrough as "incredibly exciting news". Rollout could be expected before Christmas if the jab is approved, with four million doses manufactured and ready to go when authorised, with a further 15 million set to be available in the UK before the end of the year.
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AstraZeneca plans to have 700 million doses of the jab globally by the end of March.
Tom Keith-Roach, president of AstraZeneca UK, said: “Where we stand today is we have four million doses available right now and we’ve got enough active that we think we will be able to make a further 15 million available to the UK by the end of this year."
Researchers said the vaccine has been shown to work in different age groups, including the elderly.
The announcement has been hailed as "another step closer to the time when we can use vaccines to bring an end to the devastation" of the pandemic.
Sarah Gilbert, professor of vaccinology at the University of Oxford, said: "We will continue to work to provide the detailed information to regulators. It has been a privilege to be part of this multi-national effort which will reap benefits for the whole world."
The UK also has orders for 40 million doses of a jab from Pfizer and BioNTech, which has been shown to be 95% effective.
Prof. Gilbert explains why we should not make comparisons between the vaccines
Another jab from Moderna is 95% effective, according to trial data.
There is a great deal riding on the Oxford AstraZeneca vaccination - and not just for the UK.
The Oxford jab's accessibility and affordability could, potentially, have a greater effect on fighting the pandemic than the Pfizer and Moderna vaccines.
Unlike the Pfizer and Moderna vaccines, the Oxford AstraZeneca jab is being sold at cost price at around $4 and $5 (£3/£4) a dose; in contrast Moderna said it will be charging $32 to $37 (£24/£28) a dose putting mass vaccination programmes out of financially reach for lower-income nations.
AstraZeneca chief executive Pascal Soriot, said: "Today marks an important milestone in our fight against the pandemic. This vaccine's efficacy and safety confirm that it will be highly effective against Covid-19 and will have an immediate impact on this public health emergency. "Furthermore, the vaccine's simple supply chain and our no-profit pledge and commitment to broad, equitable and timely access means it will be affordable and globally available, supplying hundreds of millions of doses on approval."
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In a statement on Twitter, Mr Johnson wrote: “Incredibly exciting news the Oxford vaccine has proved so effective in trials. There are still further safety checks ahead, but these are fantastic results. Well done to our brilliant scientists at @UniofOxford & @AstraZeneca, and all who volunteered in the trials.”
Sarah Hurst, 47, took part in the AstraZeneca and Oxford University research, receiving two jabs of either the experimental vaccine or a placebo.
She said there was a “tiny sense of pride” at her involvement, but paid tribute to the scientists and researchers who developed the vaccine.
Ms Hurst, a journalist from Goring-on-Thames in South Oxfordshire, told the PA news agency: “It’s really the developers and everyone who’s done all the work, all the medical students who are constantly all day meeting the vaccine participants and testing them and being on the front line.
“But it’s good, it’s a great feeling to help to make a vaccine.”
Health Secretary Matt Hancock called the data from AstraZeneca and Oxford University “really encouraging news”, but stressed that vaccines need to be approved by the Medicines and Healthcare products Regulatory Agency (MHRA).
He told ITV News: "The next step is that the independent regulator needs to check the data, especially check that it is safe. But if that goes well, then we can start the rollout next month. The bulk of the rollout will be in the new year, but it's a really, really good sign of progress.”
Mr Hancock said it was "even more promising" that the vaccine appeared to prevent transmission.
The shadow health secretary told ITV News it was "really, really good news" but said it was crucial resources were in place for a "deployment on a scale that is unparalleled".
"Congratulations to the scientists and those who took part in the trials, it's such good news. It's another vaccine in our locker. What we need now is a deployment plan, because it's not vaccines themselves that save lives, it's vaccination."
Peter Horby, professor of emerging infectious diseases and global health at the University of Oxford tweeted: “Oxford jab is far cheaper, and is easier to store and get to every corner of the world than the other two.”
Professor Pollard said not enough time has passed to know if people are still protected from the virus a year after being vaccinated. "We only started giving the second doses of vaccine in the UK in August. The increase in disease, as you know, started towards the end of September and so most of the cases have only relatively recently accumulated both in the UK and in Brazil. "So that means we just have not had enough time yet to be able to say whether, a year later, people are still as protected as they were at the beginning. So I think this is a 'watch this space' question." Why are there different figures being given as to the vaccine's effectiveness?
"Seventy percent is the average of two different ways of dosing the vaccine. In the “full dose” dosing regime it was 62% effective. In the one half-dose and one full dose regime it was, counterintuitively more effective — around 90% Doses given 1 month apart."
The half-dose regimen could also means there would be more available vaccine, he said.
"The 100m doses the UK government as ordered would effectively become 150m. However what the regimen looks like could change. As the Oxford team state: “More data will continue to accumulate...refining the efficacy reading and establishing the duration of protection”