London(CNN) Britain is facing a "tidal wave" of infections from the new Omicron coronavirus variant, ministers have warned, as they sound the alarm on rapid transmission rates in London and across the country.
On Monday, UK Prime Minister Boris Johnson confirmed the country's first death of a person with the variant.
Health Secretary Sajid Javid said on Monday that there were 4,713 confirmed cases of Omicron in the UK, adding that the current number of daily infections is estimated to be around 200,000.
"While Omicron represents over 20% of cases in England, we've already seen it rise to over 44% in London and we expect it to become the dominant Covid-19 variant in the capital in the next 48 hours," Javid told Parliament on Monday.
Earlier on Monday, he told Sky News: "It's spreading at a phenomenal rate, something that we've never seen before -- it's doubling every two to three days in infections." He added that it was too soon to tell if cases of the new variant are milder.
The United Kingdom increased its Covid-19 alert level on Sunday and is once again accelerating its rollout of booster jabs in an effort to respond to the new wave of cases.
"That means we're facing a tidal wave of infection, we're once again in a race between the vaccine and the virus," Javid added, echoing language used by Johnson in a televised address on Sunday night.
On Sunday, the Prime Minister set a new target of offering all adults a third shot by the end of December -- a month earlier than originally planned. He had previously cut the interval between second and third doses from six months to three. The British government has focused its Covid response around the vaccine program since last summer, and had resisted reimposing restrictions until the Omicron variant came to light.
"I'm afraid it is now clear that two doses of vaccine are simply not enough to give the level of protection we all need," Johnson said, citing early data that showed the effectiveness of a two-dose regimen is diminished by the new variant, but that boosters still provide a good level of protection.
"No-one should be in any doubt: There is a tidal wave of Omicron coming," Johnson said. "But the good news is that our scientists are confident that with a third dose -- a booster dose -- we can all bring our level of protection back up."
Javid said 10 people had been admitted to hospital with the new variant. The UK's Health Security Agency confirmed they were spread around the country and aged between 18 and 85, while the majority had received two vaccine doses.
New guidelines asking people to work from home came into force on Monday. The UK has also brought back its mask mandate for shops and public transport, and now requires proof of vaccination or a negative test for attendees of large events.
Javid said on Monday that in the future Britons will need to have had a third vaccine shot to qualify for a valid "Health Pass," which is needed to enter nightclubs and large venues. He did not go into detail about when that will become mandatory, but said it would be "once all adults have had a reasonable chance to get their booster jab."
The recent flurry of new restrictions marks a sharp turn from the past few months, during which Johnson resisted Europe's turn towards long-term mitigation measures like vaccine passports and mask mandates.
But the embattled Prime Minister has faced a significant rebellion from his own Conservative backbenchers over his move to reintroduce Covid rules, relying on support from the opposition Labour Party to pass them into law.
Johnson is also embroiled in a scandal over reports that Downing Street held a number of staff parties last winter when the rest of the UK was living under strict rules banning social mixing. He has been forced to deny he fast-tracked Covid rules in order to distract from his political woes.