The UK recorded 51,342 cases and 161 deaths on Wednesday, according to the latest daily figures.
It is the highest number of daily infection since October 21 and brings the total to 10,610,958.
The jump in fatalities brings the total to 145,987.
Elsewhere, a further 391,050 third doses of the Covid vaccine were given out on Tuesday. It brings the total number of booster shots given out to 21,300,859.
And 28,375 second doses were given out, meaning that 46,610,800 Britons are now fully vaccinated against the disease.
The figures come amid reports ministers will imminently introduce Plan B measures to curb the spread of the Omicron variant.
Downing Street sources insisted “no decisions have been made” but there is widespread speculation that further measures could be introduced on Wednesday evening following a meeting of the Cabinet’s Covid operations (Covid-O) committee.
Leaked minutes of a Sage meeting held on Tuesday said the Government should “urgently” consider the need for measures to reduce transmission of the virus and protect the NHS from “unsustainable pressure”, the BBC reported.
Professor Neil Ferguson, from Imperial College London, said another lockdown to deal with the threat of the variant could not be ruled out.
Speaking in a personal capacity, he told BBC Radio 4’s Today programme: “Certainly case numbers of Omicron are doubling at least every three days, maybe even every two days at the moment, so it’s accelerating very fast.
“It’s likely to overtake Delta before Christmas at this rate, precisely when is hard to say.”
Prof Ferguson, whose modelling was crucial in the government’s decision to lockdown in March 2020, said the peak of this wave of infection will be in January if no measures are taken to slow it down.
“So if you don’t do anything at the current time, it will most likely be some time in January,” he said.