The ramped-up rollout of Covid booster jabs will be in place by December 13, NHS England has said.
The Joint Committee on Vaccination and Immunisation (JCVI) said that all adults should become eligible for boosters and that the time between a second dose and booster should be reduced from six months to three months, in a move designed to help protect against the new Omicron variant of Covid.
But the booking service for the jabs is yet to be updated.
In a letter from the health service released on Friday, it was revealed this would be updated to reflect the reduction of the time between doses to three months “as soon as possible and no later than December 13”.
It said the jabs would be delivered “in descending age groups, with priority given to the vaccination of older adults and those in a Covid-19 at-risk group first”.
It is understood the rollout could begin earlier, as soon as the UK Health Security Agency updates its guidance.
And it confirmed that there were “no supply challenges” with either Moderna or Pfizer booster stocks.
GP surgeries have been given permission to defer routine health checks for those aged 75 and over to free up capacity to deliver the vaccines, while the Army and “clinical students” could also be called on to help deliver the jabs.
And while it was recognised that the health service was already under pressure, the letter stressed there was a “new national mission” after ministers set the challenge for the NHS to offer boosters to all adults in just 62 days.
It comes as the first case in Wales of the Omicron variant was confirmed.
The case is in the Cardiff and Vale University Health Board area and is linked to international travel, the Welsh Government said.
While figures showed Covid-19 infections have increased in all four UK nations and remain close to record levels, though the latest rise is not linked to the arrival of the Omicron variant.
Around one in 60 people in private households in England had Covid-19 in the week to November 27, up from one in 65 the previous week, according to estimates from the Office for National Statistics (ONS).
The proportion of people in England who were estimated to have coronavirus at the peak of the second wave in early January was one in 50.
This led to a surge in hospital admissions and deaths, along with a nationwide lockdown.
However, No 10 ruled out making vaccines compulsory, as has been seen in Austria and is being considered in Germany.
A spokesman for the Prime Minister told reporters: “We’ve set out our policy on this and we’ve said it’s not something that we would look to introduce.
“You’re aware of the changes we made in terms of social care settings and for NHS workers, given the importance of protecting the most vulnerable in our society.
“But there’s no plans above and beyond that in that regard.”
He said: “Our priority is to continue to promote vaccinations and promote boosters now that we are rolling out more and more boosters to more and more people.
“That is our priority, that’s our focus, and that’s what we’re asking people to come forward and take.”
Meanwhile, partygoers were urged to “keep calm and carry on” with their Christmas festivities despite scientists raising the alarm about the risks associated with gathering for social events.
Conservative Party chairman Oliver Dowden said his party had no intention of cancelling its own Christmas drinks, and others should continue with their celebrations.
No 10 said any staff parties held at Downing Street in the run-up to Christmas would be “private events” that would not be publicly announced.
Asked if he would inform reporters if there were plans for a Christmas party for staff, the Prime Minister’s spokesman said: “Obviously, events that happen in No 10 that are private events, we wouldn’t inform you.
“We obviously wouldn’t set out details of private functions in No 10 but, as I say, there will be festive events in the run-up to Christmas.”
It comes after Prime Minister Boris Johnson who received his booster dose of the Covid vaccine on Thursday, urged the public to “continue as they are” within the new measures introduced to stop the spread of the virus, following the emergence of the Omicron variant.
Senior Tories, including Health Secretary Sajid Javid have looked to encourage the public to hold firm to their pre-Christmas plans, with the hospitality industry warning it had suffered a “slew of cancellations” after Omicron sparked fresh safety fears.
Mr Dowden told Sky News: “The message to people, I think, is fairly straightforward – which is: keep calm, carry on with your Christmas plans.”