The UK has reported more than 100,000 daily coronavirus cases for the first time since mass testing was rolled out.
A total of 106,122 new infections were recorded on Wednesday, according to official government data.
Daily cases have been climbing at speed since the emergence of the Omicron variant, which is significantly more transmissible than previous strains.
The seven-day rolling average of new daily cases is 59% higher than this time a week ago.
Infection rates are highest in London, which has been hit hardest by the Omicron outbreak so far.
Read more: 15 COVID hotspots as cases explode in London
Boris Johnson has reassured people that no further curbs will be introduced in England before Christmas Day despite the rising COVID cases.
He said on Tuesday that there was currently not enough evidence on the severity of the Omicron variant and hospital admission to justify stricter measures.
On Wednesday, two studied were published suggested that Omicron is less likely to cause hospitalisations than Delta, but that the sheer number of Omicron cases means the NHS is still at risk of being overwhelmed.
Professor Neil Ferguson of Imperial College London said of his team's research: "Our analysis shows evidence of a moderate reduction in the risk of hospitalisation associated with the Omicron variant compared with the Delta variant.
"However, this appears to be offset by the reduced efficacy of vaccines against infection with the Omicron variant.
"Given the high transmissibility of the Omicron virus, there remains the potential for health services to face increasing demand if Omicron cases continue to grow at the rate that has been seen in recent weeks."
With the situation constantly being reviewed, health secretary Sajid Javid advised everyone to “remain cautious” while health minister Gillian Keegan warned there is “uncertainty” around people making new year’s eve plans.
Watch: Wales tightens COVID rules as it criticises 'paralysis of a UK government'
In Wales, first minister Mark Drakeford has announced new measures to be introduced from 6am on Boxing Day and claimed Johnson and his Cabinet are “paralysed by their internal divisions”.
He said: “I believe the UK Government sees all the data we see and gets all the advice that we get about the need to act and act urgently in the light of the Omicron wave coming our way.”
The new measures in Wales include two-metre social distancing, the rule of six, table service, face coverings in hospitality settings at all times apart from when seated and a maximum number of 30 people at an indoor event and 50 outdoors.
There will be an exception for team sports, where up to 50 spectators will be able to gather in addition to those taking part.
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On Tuesday, Sir Jeremy Farrar, a former member of the Scientific Advisory Group for Emergencies (Sage), warned that the Omicron variant is spreading “unbelievably fast” and transmission is “eyewateringly high”.
He told BBC Radio 4’s Today programme that the government may need to introduce “draconian” restrictions before Christmas.
Sir Jeremy said: “Omicron is spreading unbelievably fast. It is a phenomenal variant transmission.”
England is now left as an outlier when it comes to post-Christmas restrictions given the Northern Ireland executive will also decide on Wednesday what “level of asks” will be made of the public to curb the latest surge in COVID-19.
In Scotland, first minister Nicola Sturgeon has already introduced new curbs on hospitality while live sports will be “effectively spectator-free” for three weeks from Boxing Day.
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