New data which suggested that Omicron may be less likely to lead to serious illness than the Delta variant offers a "glimmer of Christmas hope", a senior UK health official has said.
UK Health Security Agency chief executive Dr Jenny Harries warned that it was too early to downgrade the threat from the new variant, which is still spreading rapidly across the UK and Ireland.
"There is a glimmer of Christmas hope in the findings that we published yesterday, but it definitely isn't yet at the point where we could downgrade that serious threat.
"What we have got now is a really fine balance between something that looks like a lower risk of hospitalisation - which is great news - but equally a highly transmissible variant and one that we know evades some of our immune defences," she said.
Dr Harries told BBC Radio 4's Today programme that more information is needed still, particularly about the impact on elderly and more vulnerable patients.
The rapid spread of Omicron has seen it become the dominant strain across the UK where cases were still doubling across most regions of the country.
The health agency's analysis came as the UK experienced another record-breaking number of daily reported Covid cases with 119,789 reported yesterday.
"We're not seeing very significant rises in intensive care utilisation or in the use of ventilation beds in the UK"
Dr Harries said key pieces of information about Omicron are needed to understand how much of a risk it poses to the health service, such as average length of stay in hospital.
"We're not seeing very significant rises in intensive care utilisation or in the use of ventilation beds in the UK.
"That may be because a lot of the people who've been infected to date are actually younger people and we will see that coming through," she said.
Dr Harries also suggested the Government might consider whether new restrictions are needed in England based on the wider impact of the Omicron wave, rather than just the severity of the illness.
British Prime Minister Boris Johnson has not imposed any further restrictions for England over Christmas, but has indicated he will not hesitate to act afterwards - with Monday 27 December expected to be the first opportunity to consider if changes are needed.
Dr Harries said that UK ministers will look at all of the data available to look at how the virus is impacting society.
"For example we have very high rates of individuals off sick - we know that particularly in London, around one in 35 have currently got Omicron.
"Now that's having an impact on the workforce, these are not simply about hospitalisation rates."
UK ministers are being kept updated on a daily basis and Dr Harries confirmed that this would continue throughout the Christmas period.
Her comments come after Mr Johnson used his Christmas message to urge people to come forward to get a Covid booster jab as part of the "neighbourly" spirit of the festive season.
UK virus cases hit new record
Meanwhile the UK has announced a new record number of virus cases fulled by the Omicron variant.
The government reported 122,186 new cases in the last 24 hours, more than 2,000 higher than yesterday's figure.
The UK is among the worst hit countries in Europe with a virus death toll of 147,857.
Case numbers surged 48% over the last week, as compared to the previous week, while hospitalisations and death figures have risen much less sharply.
