Jenny Harries, head of the UK Health Security Agency, said the impact on society of Omicron will be crucial despite mounting evidence that it is generally milder than the Delta strain.
Jeremy Farrar, a former SAGE member, pointed out that while another booster is already being mooted in the UK, many around the globe have yet to receive a first jab.
Cases hit a high for the second day running, with 119,789 reported in 24 hours - up 35 per cent on the last Thursday and putting a dampener on hopes that the variant could be less of a threat.
Boris Johnson has delayed decisions on toughening up Covid rules until after Christmas Day with the government stressing that there is not yet compelling evidence on whether they are needed.
Fewer hospitalisations with Omicron variant than Delta but 'its impact cannot be underestimated' leicestermercury.co.uk - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from leicestermercury.co.uk Daily Mail and Mail on Sunday newspapers.
Six things you need to know in Wales as Covid revealed to be three times as prevalent in children under 11 walesonline.co.uk - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from walesonline.co.uk Daily Mail and Mail on Sunday newspapers.
Professor Neil Ferguson found the mutant strain was up to 45 per cent less likely to lead to hospitalisation - supporting Boris Johnson s decision to delay imposing restrictions.
The report's authors described their analysis as "an initial step towards assessing the clinical severity and risk posed by the Omicron variant". | ITV National News