Boris Johnson urged people not to cancel Christmas parties or school nativity plays.
He promised to “throw everything” at the booster vaccination campaign to tackle the spread of the Omicron coronavirus variant.
The Prime Minister promised everyone eligible would be offered a jab by the end of January with at least 400 military personnel helping the NHS, and vaccination centres “popping up like Christmas trees”.
Mr Johnson rejected a call from a senior health official to limit socialising in the run-up to Christmas, insisting he had already put in place a package of “balanced and proportionate measures” in response to the threat posed by the new variant.
Asked whether parties and Nativity plays should be scrapped, Mr Johnson said: “We don’t want people to cancel such events and we think that, overwhelmingly, the best thing for kids is to be at school, as I have said many times throughout this pandemic.
“What we are doing is trying to take a balanced and proportionate approach to the particular risk that seems to be posed by Omicron – certainly is posed by Omicron – focused in particular on measures at the border.”
But as cases of Omicron reached 22 in the UK, Health Secretary Sajid Javid said they were likely to go higher and “we have to be realistic” that there is already likely to be transmission of the new strain within the community.
The mandatory wearing of face coverings in shops and on public transport came into force in England on Tuesday morning, along with tighter testing requirements for international travel and the return of self-isolation for contacts of confirmed Omicron cases, even if they have been fully vaccinated.
But it is the booster campaign which the Government believes provides the greatest line of defence against Omicron and Mr Johnson used a Downing Street press conference to promise another “great British vaccination effort” to deliver millions of jabs.
“We’re going to be throwing everything at it, in order to ensure that everyone eligible is offered that booster in just over two months,” he said.
Mr Javid said the booster programme would be put “on steroids” to meet the target, while NHS England’s chief executive Amanda Pritchard said staff are working at “breakneck speed”.
The announcement of the rapid expansion of the booster campaign came as Downing Street was embroiled in a row with a senior health official over her suggestion that people should limit social contacts in the run-up to Christmas.
UK Health Security Agency (UKHSA) chief Dr Jenny Harries said: “If we all decrease our social contacts a little bit, actually that helps to keep the variant at bay.”
The comments caused alarm in the hospitality industry and helped fuel a Tory backbench revolt which saw Conservatives rebel over restrictions which came into force in England on Tuesday morning to tackle Omicron.
Dr Harries told BBC Radio 4’s Today programme that even if our “vaccines appear to be effective, but we find that the variant is more highly transmissible, having lowish grade infection, but in very large numbers of the population, (it) could still be a significant impact on our hospitals.
“And, of course, our behaviours in winter and particularly around Christmas, we tend to socialise more, so I think all of those will need to be taken into account.”
Asked whether people should be told to work from home in England, as is happening in Scotland, Wales and Northern Ireland, she said: “We’ve seen that not everybody has gone back to work and I’d like to think of it more in a general way, which is if we all decrease our social contacts a little bit, actually that helps to keep the variant at bay.”
She suggested “being careful, not socialising when we don’t particularly need to” and getting a booster jab.
Kate Nicholls, chief executive of the UKHospitality trade body, said this “chilling talk” could hammer the sector ahead of its busiest period.
She said bookings have already been “cancelled and plans changed” by some customers.