The NHS will be ready to start vaccinating people against coronavirus next month - if one is approved by regulators - the health secretary has said.
Speaking at a Downing Street news conference on Friday, Matt Hancock revealed the government has now taken the "first step" for authorising a COVID-19 vaccine in the UK.
Ministers have formally asked the Medicines and Healthcare products Regulatory Agency (MHRA) to assess the Pfizer/BioNTech vaccine for use in the UK.
The jab has demonstrated an efficacy rate of 95% in the companies' phase 3 clinical study.
It comes as Pfizer/BioNTech made an emergency request to US regulators seeking authorisation to begin distributing millions of doses of its BNT162b2 vaccine to high-risk populations.
Pfizer chairman and CEO Albert Bourla called the submission a "historic day for science".
"It is with great pride and joy, and even a little relief, that I can say that our request for emergency use authorisation for our potential COVID-19 vaccine is now in the FDA's (Food and Drug Administration) hands," he said in a statement.
Mr Hancock said the companies had already begun submitting data to the MHRA and would submit their full data in the coming days.
"This is another important step forward in tackling this pandemic," the health secretary added.
"If a vaccine is approved it will, of course, be available across the UK from our NHS, free at the point of delivery according to need and not ability to pay."
Mr Hancock said, if the MHRA approves a vaccine, "we will be ready to start the vaccination next month, with the bulk of the roll-out in the New Year".
He added: "We're heading in the right direction, but there's still a long way to go - coronavirus remains a grave danger right now."
The news conference came as it was announced that a further 511 people had died after testing positive for COVID-19, with another 20,252 confirmed coronavirus cases in the UK.
England's deputy chief medical officer said he believed the UK was on the "glide path" towards rolling out a vaccine.
However, Professor Jonathan Van-Tam - who appeared at the news conference remotely as he is self-isolating after a "household contact" - warned delivering a vaccine might not be "totally straightforward".
He added: "Do I accept that sometimes when you are on the glide path you can have a side wind and the landing is not totally straightforward, totally textbook? Of course."
Prof Van-Tam warned that infection rates would "go back up again" if people did not follow coronavirus restrictions put in place around Christmas.
But he dismissed the idea there was a "magic number" of how many days of further restrictions would be needed for each day COVID rules might be loosened over the festive period.
Earlier this week, it was suggested England might face nearly a month-long extra lockdown in exchange for five days' release from restrictions over Christmas.
The UK government and the devolved administrations in Scotland, Wales and Northern Ireland have held talks on a joint approach for Christmas, with all four nations hoping to ease current restrictions so as to allow families to gather in greater numbers.
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But Mr Hancock said it was "still too early to tell" what rules might be in place over Christmas, or what restrictions might be required once England's current lockdown ends on 2 December.
"I'm afraid we still haven't made those decisions," he said.
The health secretary said he was "more and more confident" that life will be closer to normal by spring.
And he added the UK was "clearly near the peak" of the second wave of coronavirus infections.
Earlier on Friday, the Office for National Statistics (ONS) said the incidence rate of COVID-19 appeared to have "levelled off" in England and Scotland.
It also said rates had been decreasing in Wales and Northern Ireland.
Meanwhile, the government's Scientific Advisory Group for Emergencies (SAGE) said the reproduction number - or R value - for the whole of the UK had dropped to between 1 and 1.1.
