Coronavirus vaccines will be not be made compulsory in the UK but everyone should get a jab as soon as they are available, Boris Johnson has said.
The Prime Minister made it clear that no one would be forced to be vaccinated, saying: "That's not the way we do things in this country".
However he tore into anti-vax propaganda and said everyone should be "very, very pro vaccine".
Speaking at a Downing Street press conference, Mr Johnson estimated that the majority of people could be inoculated by Easter if there was "a favourable wind".
It comes amid growing optimism over the prospect of workable vaccines, with encouraging preliminary results from jabs developed by pharmaceutical giant Pfizer and the US firm Moderna.
On Monday, the team behind the Oxford University-AstraZeneca vaccine said their jab was proven to be 70% effective.
The Prime Minister warned the public "we're not out of the woods yet", saying: "We can hear the drumming hooves of the cavalry coming over the brow of the hill but they are not here yet."
And he said "it will be months before we can be sure we have inoculated everyone that needs a vaccine".
But with a "favourable wind", the majority of people who need a vaccine most should be able to get one by Easter.
"That would make a very substantial change to where we are at the moment," he said.
"I don't want to give any more hostages to fortune than that, but that's the best information we have."
He ruled out making jabs mandatory and said the public should want to get vaccinated.
Mr Johnson, who is self-isolating in Downing Street, told the press conference: "Let's be clear, there will be no compulsory vaccination. That's not the way we do things in this country.
"We think it's a good idea. I totally reject the propaganda of the anti-vaxxers - they are wrong.
"We should be very, very pro vaccine."
"Vulnerable people, people who need a vaccine, they should definitely get a vaccine. Everybody should get a vaccine as soon as it is available, according to the Joint Committee on Vaccination and Immunisation.
England's chief medical officer Professor Chris Whitty echoed the Prime Minister's words and urged people to get vaccinated when they can.
He said: "My advice - any medical practitioner's advice - would be these should be voluntary vaccinations.
"People should want to take them because they will protect them from a potentially very debilitating - and in some cases, sadly, fatal - disease."
Professor Andrew Pollard, of the Oxford Vaccine Group, said trial data suggested their vaccine could help prevent asymptomatic infections.
"There is a hint in the data that, in one of our groups that had the higher efficacy, we were able to reduce the amount of asymptomatic infection," he said.
"That may mean that there could be fewer people in the population who are spreaders.
"And that starts to stop the virus in its tracks, if we can get there."
