The UK recorded 37,681 Covid cases and 51 deaths on Sunday, according to the latest daily figures.
It is lower than Saturday’s total of 39,567 but higher than last Sunday’s tally of 36,433.
The rise in cases brings the total to 10,146,915 since the beginning of the pandemic, while 144,775 deaths have been reported.
Elsewhere, a further 450,480 third doses of the Covid vaccine were given out on Saturday - the highest daily tally in a week. It brings the total number of booster shots given out to 17,581,331.
And 31,679 second doses were given out, meaning that 46,309,909 Britons are now fully vaccinated against the disease.
The figures come as the a third case of the Omicron variant was detected in the UK on Sunday afternoon.
The individual, who is no longer in the UK, visited central London while they were infectious.
Health officials said they had been in Westminster in central London and the infection was “linked to travel to southern Africa”.
Dr Jenny Harries, UKHSA chief executive, said: “It is very likely that we will find more cases over the coming days as we are seeing in other countries globally and as we increase case detection through focused contact tracing.
“It’s critical that anyone with Covid-19 symptoms isolates and gets a PCR test immediately.”
New rules mandating the wearing of face coverings in shops and public transport will come into force from Tuesday, health secretary Sajid Javid has confirmed.
Those entering the UK must book a PCR test on day two after arrival and self-isolate until they get a negative result. Anyone with a suspected case of Omicron must enter a ten-day quarantine regardless of their vaccination status.
Mr Javid said he hoped the extra measures will be “temporary”, adding he thinks people will “take this more seriously”.
