A coronavirus vaccine developed in the UK can prevent up to 90 per cent of people from getting Covid-19, according to new data.
AstraZeneca and Oxford University announced that their jab is effective in preventing many people getting ill and has been shown to work in different age groups, including the elderly.
One of the dosing patterns used by the scientists suggested 90 per cent effectiveness if one half dose is given followed by a further full dose.
Another dosing pattern showed 62 per cent efficacy when one full dose is given followed by another full dose.
The combined analysis from both dosing regimes resulted in an average efficacy of 70.4 per cent.
Health Secretary Matt Hancock told BBC Breakfast that the Medicines and Healthcare products Regulatory Agency (MHRA) would now assess if the 90 per cent effectiveness dosing regime could be used.
He said: "I'm really very pleased, I really welcome these figures - this data that shows that the vaccine in the right dosage can be up to 90 per cent effective.
"Of course, it's vital that the independent regulator, the MHRA, will need to look at the data, will need to check to make sure that it's effective and safe of course.
"But we've got 100 million doses on order and. should all that go well, the bulk of the rollout will be in the new year."
Prime Minister Boris Johnson tweeted: "Incredibly exciting news the Oxford vaccine has proved so effective in trials.
"There are still further safety checks ahead, but these are fantastic results."
Professor Andrew Pollard, chief investigator of the Oxford Vaccine Trial at Oxford, 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 per cent effective and, if this dosing regime is used, more people could be vaccinated with planned vaccine supply."
Speaking on BBC Radio 4 Today's programme about the 90 per cent finding, he added: "There is just a hint in the data at the moment that those who got that regime with higher protection, there is a suggestion that it was also able to reduce asymptomatic infection.
"If that is right, we might be able to halt the virus in its tracks and stop transmitting between people."
Pascal Soriot, chief executive officer at AstraZeneca, said the news is an "important milestone" in the fight against the pandemic.
He added: "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."
Sarah Gilbert, professor of vaccinology at the University of Oxford, said the announcement took everyone a step close to a time when vaccines can be used to bring an "end to the devastation" caused by Covid-19.
"We will continue to work to provide the detailed information to regulators," she said.
"It has been a privilege to be part of this multinational effort which will reap benefits for the whole world."
The UK has placed orders for 100 million doses of the Oxford vaccine - enough to vaccinate most of the population - with rollout expected in the coming weeks if the jab is approved.
It also has orders for 40 million doses of a jab from Pfizer and BioNTech, which has been shown to be 95 per cent effective.
Another jab from Moderna, of which the UK has five million doses on order, is 95 per cent effective, according to trial data.
The results from the Oxford and AstraZeneca trial showed that the arm where one half dose was given followed by a full dose at least one month apart involved 2,741 people. This was the 90 per cent finding.
The other dosing regime involving 8,895 people showed 62 per cent efficacy when given as two full doses at least one month apart.
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."
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