The R rate of the Omicron variant in the UK could be as high as 5, a top government scientist has said.
If R is greater than 1 the epidemic is generally seen to be growing; if R is less than 1 the epidemic is shrinking.
The last official estimate of the overall R rate, published by the government on Friday, estimated it to be between 0.9 and 1.1.
Susan Hopkins, the chief medical adviser at the UK Health Security Agency, told MPs on Thursday people should be aware there were “two current variants circulating”.
“One is Delta, which is remaining relatively stable in number. The other is Omicron which is increasingly very rapidly.
“With a doubling time of every two days, the R value of Omicron is estimated to be much higher.”
Hopkins told the Commons health and science committees that the “very broad brush” estimate was that it was “between 3 and 5 at the moment”.
It came as Chris Whitty, the chief medical officer, warned UK could surpass the daily peak number of people admitted to hospital with Covid and repeated his advice that people “prioritise” social engagements.
“What I’m saying is that anybody who has something that really matters to them, concentrate on that thing, and then build out from there, rather than just accepting every invitation and going to every bit of work in person,” he told MPs.
Boris Johnson echoed that advice, telling broadcasters while the government does not “want to make your choices for you about your social life”, people should be careful.
“What we are saying is people should be cautious and they should think about their activities in the run-up to Christmas – nobody wants to get Omicron and be unwell and be forced to isolate,” he said.