Another 8,044 cases of the Omicron variant of COVID-19 have been reported across the UK - a third down on Sunday's figure of 12,133.
The total cases of the new strain across the country is now 45,145, the UK Health Security Agency said.
In the daily figures, another 91,743 coronavirus cases have been reported and 44 deaths within 28 days of a positive test, official figures show.
The number of new cases is almost 9,000 higher than on Sunday.
That goes against the general trend: Monday's figure tends to be lower than Sunday's because of a delay in data reporting over the weekend.
The number of third vaccine doses administered on Sunday was 846,466, taking the total to 28,978,244.
Just over half of those aged 12 and above have now had their booster, with the proportion standing at 50.4%.
Following a lengthy cabinet meeting on Monday, Boris Johnson said he was not announcing any further COVID restrictions - yet.
But the prime minister said he was following the data "hour by hour" and warned that the rules could still be tightened in the days to come.
The data is "under constant review" and the "arguments either way are very very finely balanced", he added.
Almost two-thirds of Britons think another national lockdown is likely in the New Year, a survey suggests.
Ipsos MORI also found 62% of people expect to see a new coronavirus variant that is completely resistant to vaccines.
Only a quarter (24%) think restrictions will be lifted permanently in 2022.