The NHS will have to postpone some planned appointments in order to meet the target of giving every adult in England a Covid-19 booster jab by the end of the year.

Nursing leaders have expressed concern about the “scale and pace” of the vaccine programme expansion – which will aim to jab almost a million people every day – while a charity said the Government must ensure NHS cancer services are “prioritised and protected”.

The target for giving every adult a booster jab was brought forward by a month over fears of a “tidal wave of Omicron” that could cause “very many deaths”.

Boris Johnson, in a pre-recorded address to the nation on Sunday evening, said Britain “must urgently reinforce our wall of vaccine protection” as he set the new deadline of jabbing everyone over 18 by the new year.

He said scientists had discovered that two doses of a vaccine is “simply not enough” to prevent the spread of the new variant and that, without a lightning speed mass booster campaign, the NHS could be overwhelmed.

The mission to administer millions more jabs by December 31 will see 42 military planning teams deployed across every health region.

And as we focus on boosters and make this new target achievable, it will mean some other appointments will need to be postponed until the New Year

Extra vaccine sites will be opened and additional mobile units deployed, clinic opening hours are to be extended to allow people to be jabbed around the clock and at weekends, while thousands more vaccinators will be trained.

Mr Johnson said: “To hit the pace we need, we’ll need to match the NHS’s best vaccination day so far – and then beat that day after day.

“This will require an extraordinary effort.

“And as we focus on boosters and make this new target achievable, it will mean some other appointments will need to be postponed until the new year.

“But if we don’t do this now, the wave of Omicron could be so big that cancellations and disruptions, like the loss of cancer appointments, would be even greater next year.”

The highest number of vaccinations reported in one day in the UK was 844,285 on March 20 2021 – equivalent to vaccinating the entire population of Liverpool in one day, according to the Government website.

In a direct plea to GPs, doctors, nurses and others on the NHS front line, who he said had “worked incredibly hard” throughout the pandemic, Mr Johnson said: “I must ask you to make another extraordinary effort now, so we can protect you, and your colleagues, and above all protect your patients from even greater pressures next year.”

NHS England said GP teams will be asked to “clinically prioritise their services to free up maximal capacity” to support the Covid-19 vaccination programme, alongside delivering critical appointments such as cancer, urgent and emergency care.

It said this “might mean that for some people, routine appointments are postponed as part of the national mission to roll out boosters”.

Steven McIntosh, executive director of advocacy and communications at Macmillan Cancer Support, said everyone can play a role in reducing pressure on critical NHS care by getting vaccinated, getting a booster jab and following Covid guidelines.

“However, the Government also must not fail to ensure NHS cancer services are prioritised and protected this winter to ensure that nobody faces long waits and disruption in vital cancer care,” he said.

Pat Cullen, general secretary and chief executive at the Royal College of Nursing, said nursing staff have already played a leading role in the delivery of vaccines and stand ready to do the same again.

“However, we are concerned about the scale and pace of this expansion, given these same nurses are already facing huge demands under existing unsustainable pressures in every part of the UK health and care system,” Ms Cullen said.

Chris Hopson, the chief executive of NHS Providers, the body representing NHS trusts, said the NHS will do everything it can to deliver the “hugely ambitious” booster campaign, but is “already beyond full stretch” and will “need to reprioritise”.

He said as more hospital staff become involved it is “likely to impact on planned care, causing some additional delays”.

Every adult over 18 in England who has had a second dose of a vaccine at least three months ago will be able to have their booster from Monday, Mr Johnson said.

He said the UK Government would support the devolved administrations to “accelerate” their own rollouts of third jabs.

First Minister Nicola Sturgeon said Scotland would match the aim of offering boosters to all eligible adults before 2022, but added that more Covid-19 restrictions may still be needed to tackle the new strain.

Welsh leader Mark Drakeford also said “further steps” could be required to keep the country safe, as he encouraged people to “make having your booster a priority” amid a pledge to quicken the rollout.

Meanwhile, the UK Covid alert level was raised to Level 4, up from Level 3, following a rapid increase in the number of Omicron cases being recorded.

The recommendation was made to ministers by the country’s four chief medical officers and NHS England’s national medical director following advice from the UK Health Security Agency (UKHSA).

The UK, as of Sunday, recorded a further 1,239 confirmed cases of the Omicron mutation, bringing the total number of cases to 3,137 – a 65% increase from Saturday’s total of 1,898.

Education Secretary Nadhim Zahawi said the actual number was likely to be 10 times as high.