There are currently 10 patients with the new Omicron variant in England's hospitals, the Health Secretary has said.
Sajid Javid said he was unable to confirm any deaths from the new strain - but warned there is a lag between infections, hospitalisations and deaths.
He said there country was facing a "tidal wave" of infections as the Government launched a mammoth booster programme to battle the "Omicron emergency".
Boris Johnson gave a televised address to the nation on Sunday night, where he said two doses of a vaccine is "simply not enough" to prevent the spread of Omicron - and the NHS could soon be overwhelmed.
In a massive escalation of the jabs rollout, the PM committed to offer a booster to every adult in England by the end of the year - a month earlier than planned.
Ministers are worried by the speed of the spread of the new variant, which is expected to become the dominant Covid strain - despite only being detected in the UK last month.
Scientists are still scrambling to understand the Omicron variant but cases have risen sharply in recent days.
Asked how many people are in hospital with the new variant, Mr Javid told Sky News: "In England, there's about 10 people that are confirmed, in England, with Omicron."
He added: "At this point in time I can't confirm a death."
But he said: "There is always a lag between infection and then hospitalisation and then, sadly, death."
Mr Javid said the new variant was "spreading at a phenomenal rate, something that we've never seen before, it's doubling every two to three days in infections".
"That means we're facing a tidal wave of infection, we're once again in a race between the vaccine and the virus."
Around 40% of infections in London are now Omicron, which is expected to soon become the dominant strain.
Around 1 million jabs will have to be administered a day to meet the PM's booster target, which means other NHS care will be hit.
Mr Javid said people with cancer symptoms would unaffected by the diversion of NHS resources to the vaccine rollout - but non-urgent care would be impacted.
He said: "That might mean, for example, it might mean a knee operation or a hip operation or something... sadly someone has probably been waiting for a long time in any case, but the hospital concerned would have the right to postpone it if it meant they would get a lot more booster jabs done," he said.
Meanwhile, Mr Javid also said he could not guarantee schools would not be forced to close again due to the virus.
Asked if this was still a possibility, Mr Javid told LBC: "Well, I don't want to see that or any of these kinds of measures. I'm just going to focus on everything else we need to be doing, especially the booster programme."
He added: "I'd say this... if you are asking me for guarantees, I will just say - as the Health Secretary, of course, I'm not the Education Secretary - as the Health Secretary, that there are, when it comes to our fight against this pandemic, there are no guarantees."
Mr Javid said he was still going ahead with his Christmas plans - and he said people should "enjoy their Christmas with their family and loved ones".
But he added: "Please be cautious with this."
