A coronavirus vaccine developed in the UK can prevent up to 90% 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.
The jab could start to be rolled out in the UK from December, with the bulk of vaccination in the new year.
Another dosing pattern showed 62% 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%.
Health Secretary Matt Hancock told BBC Breakfast that the Medicines and Healthcare products Regulatory Agency (MHRA) would now assess if the 90% 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% effective.”
He added: “If this all goes well in the next couple of weeks, then we are looking at the potential of starting the vaccination programme next month for this Oxford-AstraZeneca vaccine as well as the Pfizer vaccine.
“But in all cases the bulk of the rollout will be in the new year.
“We are looking with high confidence now that after Easter things can really start to get back to normal.”
“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% 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% 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.”
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 the jab from Pfizer and BioNTech, which has been shown to be 95% effective.
Another jab from Moderna, of which the UK has five million doses on order, is 95% 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% finding.
The other dosing regime involving 8,895 people showed 62% 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.”
He said the vaccine could be stored in a fridge rather than the minus 70C to minus 80C needed for the Pfizer and Moderna vaccines.
He added: “This is very welcome news, we can clearly see the end of tunnel now.
“There were no Covid hospitalisations or deaths in people who got the Oxford vaccine.
“Although no serious reactions were reported in people who got the Oxford vaccine, we do need to await the full safety data and to monitor safety of all vaccines carefully if and when they are rolled out.
“The reported efficacy of 70% is an interim measure and, as more data accrue, we will get a better idea of the protection it affords.
“Importantly, from what we have heard the vaccine seems to prevent infection not just disease.
“This is important as the vaccine could reduce the spread of the virus as well as protect the vulnerable from severe disease.”
“The results from this trial of the Oxford/AZ vaccine are highly encouraging, demonstrating significant efficacy.
“A particular strength of this vaccine is that it can be stored in a fridge; this means that it can be distributed around the world using existing delivery mechanisms.
“This could therefore have a truly significant impact across the globe and enable an end to the Covid-19 pandemic.
“Of course much will be made of the difference in overall efficacy between this vaccine (70%) and the Pfizer and Moderna vaccines (95%).
“However, it is encouraging to see that, in a sub-analysis, a fractional dosing schedule in which the first dose was administered at a lower level than the second resulted in higher efficacy and gave results comparable to the other vaccines (90%).”
Dr Michael Head, senior research fellow in global health at the University of Southampton, said: “It’s not yet fully clear why a half dose and then a full dose was potentially more protective, but if the final results continue to show this pattern of around 90% effectiveness, this would allow greater vaccine supply not just in the UK but also globally.”