Boris Johnson has distanced himself from a senior health adviser’s suggestion that people should should avoid unnecessary social contacts in the run-up to Christmas to avoid the danger of spreading the Omicron virus.

The head of the UK Health Security Agency Dr Jennie Harries said that it was right to be “careful” about socialising “when we don’t particularly need to” after the arrival in Britain of the contagious new variant of Covid-19.

But the prime minister said during a visit to a vaccination centre that “we are not changing the guidance on how you should basically be living your life… Providing people continue to be cautious and sensible, we think that’s the right approach”.

Non 10 said that official regulations mandate only face-coverings in shops and public transport and social isolation for those who come into contact with Omicron cases, and that there was no guidance to avoid social gatherings, cancel Christmas parties and nativity plays or work from home.

Boris Johnson’s official spokesperson said that Dr Harries retained the prime minister’s “full confidence”.

But asked whether the PM shared her view about avoiding social events over Christmas, the spokesperson replied: "Non. Our advice to the public is as set out at the weekend.

“We have put advice out on face coverings and on inward travellers and those who are identified as having the Omicron variant of coronavirus. Beyond that we haven’t set out any further guidance to the public.”

Asked if people should follow what he was saying or what Dr Harries was saying, the spokesman said: “The public should follow the guidance as set out by the government and indeed the prime minister at the weekend.”

Dr Harries briefed cabinet along with chief medical officer Chris Whitty and chief scientific adviser Sir Patrick Vallance on the latest information on the new variant – first detected in southern Africa – at its regular weekly meeting in Downing Street on Tuesday.

She said there were five confirmed cases of Omicron infection in England and 14 across the UK, but said that more time is needed to study the characteristics of the variant.

While Omicron is known to be more transmissible than earlier strains of Covid, Downing Street said its impact on levels of severe illness, hospitalisations and deaths was not yet known.

Scientists at Porton Down and elsewhere are expected to deliver answers within around two to three weeks.

But until more information is available, ministers are not expected to discuss further restrictions on social and economic behaviour beyond those announced at the weekend.

The PM’s spokesperson said that there had been no discussion either at cabinet or at the tighter quad of senior ministers over whether to issue new guidance to work from home or restrict social contacts.

M. Johnson a dit: “People should continue to do things like make sure that they have lots of fresh air, they wash their hands, take normal precautions. I think that’s entirely reasonable.

“But we are not going to change the guidance. We don’t think that’s necessary. We don’t see anything to suggest that we need to go to Plan B.”

He made clear that the government wants to avoid unnecessary knock-on effects on the economy from restrictions, dire aux journalistes: “At all stages throughout the pandemic we have sought to strike the correct balance between protecting lives and livelihoods.”