Boris Johnson has warned that the new Covid variant is doubling in less than two days in some regions as he warned the "wave of Omicron continues to roll in".
The Prime Minister urged the public to "give Omicron both barrels" as he appealed to the nation to get their boosters urgently to see off the spread of the new strain.
A record-breaking 78,610 new Covid cases emerged as of 9am on Wednesday - the highest daily total since the pandemic began.
Speaking at a Downing Street press conference, Mr Johnson said: "The wave of Omicron continues to roll in across the whole of our United Kingdom, with over 78,000 Covid cases today, the highest ever daily number reported.
"The doubling rate of Omicron in some regions is now down to less than two days and I’m afraid we are also seeing the inevitable increase in hospitalisations up by 10 per cent nationally week on week and up by almost a third in London."
Analysis suggests that the new Omicron variant is now the dominant strain in London.
But Mr Johnson said the extraordinary booster effort offered signs of hope.
"While hospital admissions are going up, nationwide we are starting to see admissions coming down among some of the more vulnerable older age groups where we have already got those boosters in arms," the PM said.
Booster clinics are popping up in football stadiums, shopping centres, pharmacies and GP surgeries across the country.
Mr Johnson said the Government is "throwing everything'' at the booster rollout.
He said: "We are throwing everything at it and wherever you are, we'll be there with a jab for you, so please get boosted now.''
He added: "Let’s keep going. Let’s carry on giving Omicron both barrels.
"Let’s slow its spread and give the vaccines more time."
Mr Johnson insisted the Government was taking the "right approach" by not bringing in new restrictions.
He added: "We’re also using a tool we didn’t have a year ago ... not just testing but the booster".
There is mounting alarm in Government about the rapid spread of the Omicron variant, with officials privately not ruling out fresh restrictions.
On Sunday, the Prime Minister announced a massive expansion of the booster programme to respond to the new strain - with jabs to be offered to all adults by New Year's Eve.
Earlier this week, the UK Health Security Agency (UKHSA) released an explosive estimate that daily infections were running at 200,000.
UKHSA boss Dr Jenny Harries warned MPs of a "staggering" number of cases over the next few days - which could plunge the NHS into "serious peril".
Speaking to the Commons Transport Committee about the testing regime for travel, she said: "Trying to prevent ingress of any infections, including Omicron, still remains a key point, particularly when we can foresee a very large wave of Omicron coming through and our health services potentially being in serious peril".
Professor Graham Medley, one of the Government's SAGE experts, said there was a real possibility the NHS could be overwhelmed by next month.
Asked if hospitals could end up overwhelmed, he told the BBC : "I think that that is a very real possibility.
"If the numbers of infections increasing continues in the way that it has done, and it spills out into older age groups, then we could see numbers of people being admitted to hospital getting very large and certainly going over the 1,000, maybe up to 2,000 a day, that we've managed to keep the Delta variant below.
"It was sort of below 1,000 since July without any restrictions, but I think that is going to be very, very difficult or are very unlikely to happen."
Pressed on the possibility of the NHS being overwhelmed next month, Prof Medley said: "I think so, there is that possibility.
"It's very hard to be certain about these things. You certainly can't put a risk or probability on them, but that is one of one of the more likely things that could happen."