COVID-19 infections in Britain and Northern Ireland have jumped to their highest level since the summer, with nearly three million people likely to have had the virus at Christmas.
The figures come as the UK is experiencing its worst flu season for a decade and ambulance handover delays at hospitals are at a record high.
A total of 2.97 million people in private households were likely to test positive for coronavirus in the week to December 28, according to the Office for National Statistics (ONS).
This is more than double the number at the start of the month and is the highest total since mid-July.
Around one in 20 people in England are likely to have had Covid-19 over the festive period, along with one in 18 in Wales and one in 16 in Northern Ireland.
Prevalence of the virus is slightly lower in Scotland, at one in 25 people.
Michelle Bowen, ONS head of health surveillance, said that infections have risen across the whole of the UK, with levels in Northern Ireland now at their highest since March 2022.
She added: "Across English regions, infections have increased in the North East, Yorkshire and the Humber, the East Midlands, the East of England, the South East and the South West.
"Cases have also increased in those aged two to school Year 6, and those aged 50 years and over."
Meanwhile, the Public Health Agency (PHA) was last night urged to publish guidance on the latest Covid-19 variant.
People Before Profit MLA Gerry Carroll said he is "deeply concerned" about the impact the new variant could have on "our under-pressure hospitals".
It comes after the World Health Organisation issued a warning about the so-called 'Kraken' variant, which it said was "most transmissible sub-variant" of the virus.
Mr Carroll said he had written to the PHA urging it to publish guidance on the new variant.
"This new variant is easily spread and the WHO has warned of potential mutations," he said.
"The PHA needs to urgently release guidance to help prevent the spread of Covid-19.
"Our hospitals are at breaking point thanks to years of underfunding.
"Striking health workers are doing their bit to defend the NHS, but the PHA must act to protect the public and the health service in the face of this new variant."
