Britain will call in the army to help reach the target of giving all adults a third vaccination dose against Covid-19 by the end of January.
Prime Minister Boris Johnson said England will have more than 1,500 community pharmacy sites ready to administer the doses.
Everyone eligible for a coronavirus booster jab will be offered one within two months, Mr Johnson said, as he promised “another great British vaccination effort” to tackle the Omicron variant.
He said at least 400 military personnel will help the NHS and volunteers deliver shots, with centres “popping up like Christmas trees”.
Mr Johnson told a Downing Street press conference: “We’ve already done almost 18 million boosters across the UK but we’ve got millions more to do to protect the most vulnerable.
“Then we’ll move down the cohorts rapidly, and working together with the devolved administrations we want to ramp up capacity across the whole United Kingdom to the levels we achieved in the previous vaccination effort.
“We’re going to be throwing everything at it in order to ensure that everyone eligible is offered that booster, as I say, in just over two months.”
Health Secretary Sajid Javid said the booster programme would be put “on steroids” to meet the target.
The need for action was underlined as the number of confirmed cases of the Omicron variant in the UK reached 22, with that figure expected to increase further.
The booster drive has been sparked by concerns that current vaccines will not give such good protection against the new variant, and will need to be lifted by a new round of shots.
The head of one of the world's largest drug makers and a producer of one of the vaccines used to tackle the pandemic warned that its jab would likely be affected.
Stephane Bancel, chief executive of Moderna, said that drug makers would probably have to tweak and adjust their vaccines to be effective against the new strain, a process that could take months.
Tighter restrictions to combat the spread of Omicron were introduced on Tuesday.
Face coverings are again compulsory in England in shops and settings such as banks, post offices, hairdressers, and public transport, unless people are exempt. Hospitality settings such as pubs and restaurants are not affected.
Pupils in year seven and above, teachers and visitors should wear face coverings in communal areas in schools, colleges and universities in England.
Anyone entering the UK from any destination abroad will have to take a PCR test within two days of arrival and self-isolate until they have a negative result.
Mr Johnson said the government will not keep additional Covid restrictions in place any longer than necessary.
He said: “There’ll be temporary vaccination centres popping up like Christmas trees and we’ll deploy at least 400 military personnel to assist the efforts of our NHS, alongside of course the fantastic jabs army of volunteers.
“I know the frustration that we all feel with this Omicron variant, the sense of exhaustion that we could be going through all this all over again.
“But today I want to stress this, today that’s the wrong thing to feel because today our position is and always will be immeasurably better than it was a year ago.
“What we’re doing is taking some proportionate precautionary measures while our scientists crack the Omicron code.
“And while we get the added protection of those boosters into the arms of those who need them most.”
Mr Johnson said he is getting his Covid-19 booster jab on Thursday.
As with the first jabs, health officials will work through people by age group going down in five-year bands, so that the older and the more clinically vulnerable get added protection first.
Mr Johnson told a press conference: “I’ve been waiting patiently for my moment to come. It’s happening on Thursday I’m pleased to say.
“So whenever your turn comes, get your booster and ask your friends and your family to do the same.
“It’ time for another great British vaccination effort. We’ve done it before and we’re going to do it again.
“And let’s not give this virus a second chance.”
Mr Johnson was asked if he agreed with Dr Jenny Harries, chief executive of the UK Health Security Agency (UKHSA), who urged people not to socialise if they do not need to in the run-up to Christmas, and was asked if Christmas parties should be cancelled.
He replied: “So the answer is no. The guidance remains the same, and we’re trying to take a balanced and proportionate approach.
“We’ve got the measures in place to fight Delta, which we think are appropriate, and then we’re bringing in some tougher measures to stop the rapid seeding of Omicron in this country to give us the time we need to get the boosters in and of course to find out more.”
He described the new measures as “the right balance”.
Amanda Pritchard, chief executive of NHS England, said staff are working at speed to expand the booster jab roll-out.
She said: “The NHS Covid vaccination programme was already in its most complex phase and staff are now working at breakneck speed to respond to this, the biggest change in eligibility since the programme was launched.”
Ms Pritchard said “while changes to the booking system protocols and patient group directive are put in place” the roll-out will continue to vaccinate those already eligible and she repeated Mr Johnson’s call for people “not already eligible” not to contact the NHS about a jab until they are called forward.
Health Secretary Sajid Javid said the daily number of jabs has risen by a third since the start of this month.
He said people should get vaccinated to “give ourselves the best chance of a Christmas with our loved ones”.
Mr Javid told a press conference: “What we’re seeing recently has brought back memories of the strain of the last winter. But although we can’t say with certainty what lies ahead, we have one huge advantage that we didn’t have back then: our vaccination programme, which has already done so much to keep this virus at bay.
“But these defences will only keep us safe if we use them. This is a national mission and we all have a role to play.
“If we want to give ourselves the best chance of a Christmas with our loved ones, the best thing we can all do is step up, roll up our sleeves, and get protected when the time comes.”
On Tuesday, eight further cases of the Omicron variant were confirmed in England, bringing the total number identified in the country to 13, the UKHSA said.
Nine cases have also been identified in Scotland, meaning 22 cases have been identified across the two countries.
Officials said that individuals who have tested positive and their contacts are all isolating.
Work is under way to identify any links to travel to southern Africa, the UKHSA said.
“It is very likely that we will find more cases over the coming days as we are seeing in other countries globally and as we increase case detection through focused contact tracing," Dr Harries said.
“That’s why it’s critical that anyone with Covid-19 symptoms isolates and gets a PCR test immediately.”
UKHSA said that there were now two cases in Barnet, one in Brentwood, two in Camden, one in Haringey, one in Liverpool, one in north Norfolk, one in Nottingham, one in Sutton, another in Wandsworth and two in Westminster.