A Covid-19 vaccine from Oxford University and AstraZeneca has been approved for use in the UK, paving the way for rapid rollout.
The jab, which has been described as a "game changer", was given the green light by the Medicines and Healthcare products Regulatory Agency (MHRA). The UK has ordered 100 million doses of the vaccine - enough to vaccinate 50 million people. The UK is the first country in the world to approve the vaccine, which comes as a new, more contagious variant of coronavirus spreads across the country.
AstraZeneca and other developers say they are studying the impact of the new variant but expect that their shots will be effective against it. Rollout of the vaccine will begin on January 4.
It is the second jab to be approved in the UK after the Pfizer-BioNTech vaccine in December, but the Oxford-AstraZeneca vaccine will mean a significant increase in vaccination because it is cheap and easy to mass produce.
And unlike the Pfizer-BioNTech jab, which needs to be stored at -70C, this vaccine can be stored in a standard fridge so it will be far easier to get it to care homes and GP surgeries. More than 600,000 people in the UK have been given the Pfizer-BioNTech vaccine since December.
How is the Oxford Astra Zeneca vaccine made?
The Oxford vaccine (ChAdOx1 nCoV-19) is made from a virus, which is a weakened version of a common cold virus (adenovirus), that has been genetically changed so that it is impossible for it to grow in humans.
Adenovirus vaccines have been researched and used extensively for decades and have the significant benefit that they are stable, easily manufactured, transported and stored at domestic fridge temperature (2-8C so they can be easily distributed and deployed quickly.
How does the Oxford Astra Zeneca vaccine work?
Scientists have taken genes from the spike protein on the surface of coronavirus and put them into a harmless virus to make a vaccine. When injected into a person, the vaccine enters cells which then start to produce the coronavirus spike protein. This prompts the immune system to produce antibodies and activate T-cells to destroy infected cells. If the person encounters coronavirus again, the antibodies and T-cells are triggered and fight the virus.
How did the Oxford Astra Zeneca vaccine arrive "so quickly"?
One of the things you'll hear people raise regularly is that the vaccine has arrived "quickly" and therefore there should be concerns over its safety. But while this vaccine (and the Pfizer vaccine) have arrived faster than other vaccines, there are many reasons for this. None of them have to do with a lack of safety or cutting corners.
Firstly, work on a plan to tackle the world's next big pandemic began years ago, with the Ebola outbreak of 2014-6 a major accelerator.
"We were planning how can we go really quickly to have a vaccine in someone in the shortest possible time," Prof Sarah Gilbert, the architect of the Oxford vaccine, told the BBC.
Oxford researchers had already constructed ChAdOx1 (Chimpanzee Adenovirus Oxford One) which has since become ChAdOx1 nCoV-19 (the new vaccine).
As repeatedly stated by health professionals in recent weeks and months, funding is a major block to developing vaccines. But money was no object this time, with the world desperate to get out of the pandemic.
And the vaccine hasn't been rushed through trials either — they began on humans in April. And since then the vaccine has gone through all the necessary phases:
- Tested in a small number of people to check it is safe
- Tests in more people
- A big trial, involving thousands of people, to prove it actually protects people
This third stage included 30,000 volunteers, and there is as much data as any other vaccine trial.
Will the vaccine work on the new variant of coronavirus?
Oxford's Professor Andrew Pollard told the Today programme: "At the moment there's no evidence that the vaccines won't work against a new variant but that is something which we have to look at. We can't be complacent about this variant, or perhaps future variants.
"And so one of the really important things that science has to continue to do now as we move forwards is to monitor the viruses that are around, and to make sure that vaccines still are effective against them.
"If in the future, it was necessary to tweak the vaccines that's entirely possible to do, but I don't think that's something to be concerned about today, but we can't be complacent, we have to keep watching."
How will this change the course of the pandemic and our lives?
Health Secretary Matt Hancock said he has a "very high degree of confidence" that the pandemic's situation in the UK will change by the spring.
On Monday, Calum Semple, professor of outbreak medicine at the University of Liverpool and a member of the Scientific Advisory Group for Emergencies (Sage), described the vaccine as a "game changer" but said it would take until summer to vaccinate enough people for herd immunity - when the virus struggles to circulate.
"To get the wider community herd immunity from vaccination rather than through natural infection will take probably 70% to 80% of the population to be vaccinated, and that, I'm afraid, is going to take us right into the summer, I expect," he said.
Asked if he could provide a timeline for when under-50s without pre-existing conditions may be vaccinated, Mr Hancock told Times Radio: "It depends on the speed of manufacture, I wish I could give you a date, your invitation right now, but we can't because it depends on the speed of the manufacture.
"But what I can tell you is that I now have a very high degree of confidence that by the spring enough of those who are vulnerable will be protected to allow us to get out of this pandemic situation. "We can see the route out and the route out is guided by this vaccine and that's why this is such good news for everyone."
A UK Government Department of Health and Social Care spokesman said: "The Government has today accepted the recommendation from the Medicines and Healthcare products Regulatory Agency (MHRA) to authorise Oxford University/AstraZeneca's Covid-19 vaccine for use.
"This follows rigorous clinical trials and a thorough analysis of the data by experts at the MHRA, which has concluded that the vaccine has met its strict standards of safety, quality and effectiveness."
Data published in The Lancet medical journal in early December showed the vaccine was 62% effective in preventing Covid-19 among a group of 4,440 people given two standard doses of the vaccine when compared with 4,455 people given a placebo drug.
Of 1,367 people given a half first dose of the vaccine followed by a full second dose, there was 90% protection against Covid-19 when compared with a control group of 1,374 people.
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The overall Lancet data, which was peer-reviewed, set out full results from clinical trials of more than 20,000 people.
Among the people given the placebo drug, 10 were admitted to hospital with coronavirus, including two with severe Covid which resulted in one death. But among those receiving the vaccine, there were no hospital admissions or severe cases.
The half dose followed by a full dose regime came about as a result of an accidental dosing error. However, the MHRA was made aware of what happened and clinical trials for the vaccine were allowed to continue.
In an interview with the Sunday Times, AstraZeneca chief executive Pascal Soriot suggested that further data submitted to the regulator showed the vaccine could match the 95% efficacy achieved by the Pfizer/BioNTech and Moderna vaccines.
"We think we have figured out the winning formula and how to get efficacy that, after two doses, is up there with everybody else," he said.
