A coronavirus vaccine could be made available to certain groups of people in the UK by the end of the year, the Government's chief scientific adviser has said.
Sir Patrick Vallance said "good progress" is being made on developing a vaccine which can fight Covid-19.
In a televised press conference alongside England’s chief medical officer, Professor Chris Whitty, Sir Patrick said a number of candidates have shown they can generate an immune response that ought to be protective.
"Many vaccines now have shown they generate an immune response of a type that ought to be protective," he said.
“We don’t yet know they will work but there is increasing evidence that is pointing in the right direction and it is possible that some vaccine could be available before the end of the year in small amounts for certain groups.
"Much more likely that we’ll see vaccines becoming available over the first half of next year, again not certain but pointed in the right direction, which then of course gives the possibility of a different approach to this virus."
Earlier, Health Secretary Matt Hancock told ITV’s This Morning a "mass roll-out" of a vaccine could be seen in the early part of next year if all goes well.
"Hopefully in the first few months – there’s still a chance of it coming on stream before Christmas, but we’ve then got to roll it out and the first people who will get it are the people who are most vulnerable – people in care homes, older people," he said.
"There’s a series of different vaccines, but we are talking about – essentially, for it to have an impact on how we live our lives – we’re talking about the start of next year."
It came amid warnings that there could be 50,000 coronavirus cases per day next month if the spread of the disease is not brought under control.
Sir Patrick said the epidemic is doubling roughly every seven days.
"If, and that’s quite a big if, but if that continues unabated and this grows doubling every seven days… if that continued you would end up with something like 50,000 cases in the middle of October per day," he told the briefing.
"50,000 cases per day would be expected to lead a month later, so the middle of November say, to 200-plus deaths per day.
"The challenge therefore is to make sure the doubling time does not stay at seven days.
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"There are already things in place which are expected to slow that, and to make sure that we do not enter this exponential growth and end up with the problems that you would predict as a result of that.
"That requires speed, it requires action and it requires and it requires enough in order to be able to bring that down."
He said "in every age group we’ve seen an increase", adding this is not due to more testing, because of an increase in test positivity and results of the ONS study, which says around 70,000 people in the UK have Covid-19.
Sir Patrick also warned that the size of the UK population with antibodies was still low, making the "vast majority" of people "susceptible" to Covid-19.
Antibodies were not an “absolute protection” either, he said, with the immunity to the illness fading over time.
Speaking at the briefing, Sir Patrick said: “What we see is that something under 8 per cent of the population have been infected as we measure the antibodies.
"So 8 per cent, about three million or so people, may have been infected and have antibodies.
"It means the vast majority of us are not protected in any way and are susceptible to this disease."
He said antibodies in city populations was a "little higher" and that as many as 17 per cent of people in London could have them, making the spread slower in those areas.
Speaking at the press briefing, Prof Whitty also warned that the virus is not getting milder as some people have suggested.
Prof Whitty suggested science would eventually "ride to our rescue" but that in the next six months it would have to be taken very seriously.
He said: “Lots of people have said maybe this is a milder virus than it was in April.
“But I’m afraid, although that would be great if that were true, we see no evidence that is the case."