UK-made Covid-19 vaccines are on course to be ready by the end of 2020.
The Oxford University and AstraZeneca backed team says it expects to be given the go ahead on their vaccine before the year is over.
The Government has ordered 100 million doses of the vaccine, which should be easier to store and roll-out than the Pfizer jab, as the Oxford vaccine can be stored at 'fridge' temperature, rather than the -80C units required to keep the Pfizer version safe.
The 100 million jabs should be enough to vaccinate the entire UK population if it is approved. The Government has ordered 40 million of the Pfizer vaccine, which requires two doses per person.
Professor Andrew Pollard, to led the Oxford team, told The Sun : "We’re optimistic we’ll be able to demonstrate efficacy by the end of the year.
"We have been working tirelessly all year and can’t wait to see the results in the months ahead."
AstraZeneca has pledged to offer the vaccine on a not-for-profit basis.
The update comes as a leading Government advisor has said it is 'crucial' that Brits obey lockdown restrictions over the next two weeks.
Professor Susan Michie, a member of the Government's Scientific Advisory Group for Emergencies (Sage) urged the UK to stick to lockdown and social distancing rules so cases do not rise before Christmas.
She warned that positive news about vaccines should not encourage people to become complacent, start meeting up and flouting social distancing rules.
When asked which restrictions should be enforced when the lockdown ends, as it is set to on December 2, Prof Michie told BBC Radio 4's Today: "It's too early to know. I think the next two weeks is going to be absolutely crucial.
"They're going to be a very challenging two weeks, partly because of the weather, partly because, I think, the promise of a vaccine may be making people feel complacent.
"But the vaccine is very unlikely to come in until the end of the year or beginning of next year and that's going to make no difference to the current second wave.
"So I think for the next two weeks, everybody has to really get all their resolve together."
