The top scientists Joint Committee on Vaccination and Immunisation (JCVI) have said the time between a second dose and booster should be reduced from six months to three months.
But the booking service for the booster jabs is yet to be updated – with under-40s and over-40s who have not yet waited six months since their second dose still unable to make an appointment.
In a letter from the health service released on Friday, it was revealed the booking system would be updated to reflect the reduction of the time between doses “as soon as possible and no later than 13 December”.
NHS England also 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 to the older age groups set to become eligible could begin earlier than 13 December, as soon as the UK Health Security Agency updates its guidance.
Healthcare leaders have raised concerns over whether they will be able to meet Mr Johnson’s end-of-January deadline, which will mean going from 2.5 million jabs a week to 3.5 million, and still maintain routine NHS care.
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.
The health authorities have confirmed that there were “no supply challenges” with either Moderna or Pfizer booster stocks.
The new rollout details come as the first case of the omicron variant in Wales 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 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 27 November, up from one in 65 the previous week, according to estimates from the Office for National Statistics (ONS).
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: “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 … But there’s no plans above and beyond that.”
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.
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