Prime minister Boris Johnson has urged people to wait for the NHS to contact them before trying to book their Covid booster jab.

In a press conference at Downing Street this afternoon, the prime minister said vaccinations were the best weapon against rising cases of the Omicron variant and set a target for all eligible people to receive a booster by the end of January.

Mr Johnson said: “The target that we’ve set ourselves is to offer a booster to everyone eligible by the end of January.

“As with the first jabs, we will be working through people by age group going down in five-year bands, because it is vital that the older and the more clinically vulnerable get that added protection first.

“So, even if you have had your second jab over three months ago and you are now eligible, please don’t try and book until the NHS says it is your turn."

Mr Johnson went on to add that despite 18 million boosters offered across the UK, there are still "millions more to do" in order to protect the most in need.

“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," the prime minister continued.

“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.”

The prime minister was joined by health secretary Sajid Javid and NHS chief executive Amanda Pritchard at the press conference.

Mr Javid said the best way to avoid a Christmas lockdown was for people to take up the offer of a booster jab — with third doses soon to be made available to all adults over 18.

"What we’re seeing recently has brought back memories of the strain of the last winter," the health secretary said.

"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.”

Mr Johnson confirmed England will have more than 1,500 community pharmacy sites with a number of temporary vaccination centres also being set up.

"There will 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," he said.

“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.”

The announcement comes after new rules came into force today making face masks mandatory in shops and on public transport.

From today, all new arrivals into the UK will also be subject to more Covid-19 testing before entering the country.