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.
There were no hospitalised or severe cases in anyone who received the vaccine.
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.
Professor Andrew Pollard, director of the Oxford Vaccine Group and chief investigator of the Oxford Vaccine Trial, said that they had developed an “effective vaccine”.
“These findings show that we have an effective vaccine that will save many lives,” he said. “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.
“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.”
He said that no-one who had received the Oxford vaccine in the trials had required hospital treatment for Covid-19.
“We are really pleased with these results,” he told the BBC Radio 4 Today programme.
“What we have got is a vaccine that is able to protect against coronavirus disease and, importantly, there were no hospitalisations or severe cases in anyone who had the Oxford vaccine.
“So, that means that if we did have people vaccinated then certainly so far the results imply that we would be able to stop people getting severe disease and going into hospital.”
His colleague, Professor Sarah Gilbert, professor of vaccinology at the University of Oxford, said: “The announcement today takes us another step closer to the time when we can use vaccines to bring an end to the devastation caused by SARS-CoV-2. 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.”
AstraZeneca chief executive Pascal Soriot said the vaccine’s simple supply chain and no-profit pledge means it will be “affordable and globally available”.
“Today marks an important milestone in our fight against the pandemic”, he said.
“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.”
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).
“This is really encouraging news on the Oxford AstraZeneca vaccine, that obviously we’ve been backing since the start,” he told Sky News.
“And I’m really very pleased, really welcome these figures, this data, that show that the vaccine in the right dosage can be up to 90% 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.”
“So having two vaccines that appear to have effectiveness, done right, in the 90% range is really, really good news.”
Business Secretary Alok Sharma said the results were “very promising”.
He tweeted: “Very promising data from the Oxford/AstraZeneca Phase III clinical trials. We are on the cusp of a huge scientific breakthrough that could protect millions of lives. The UK has secured early access to 100m doses of their vaccine – on top of 255m doses from other developers.”
Scientists welcomed the news from the Oxford/AstraZeneca Covid vaccine trial.
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.”
Dr Michael Tildesley, associate professor in infectious disease modelling at the University of Warwick, told Times Radio: “It’s absolutely excellent news about the Oxford vaccine because this is really the vaccine that the Government has pinned a lot of their hopes on in terms of resources – we’ve ordered 100 million doses of the Oxford vaccine.”