The R-rate for the Omicron coronavirus variant could be as high as 3.47, preliminary research suggests.

Professor Alastair Grant, from the University of East Anglia, has predicted the reproduction rate of the new variant based on figures from the UK Health Security Agency (UKHSA).

He said the high figure for Omicron is due to “a mixture of it being good at transmitting itself and being a partial vaccine escape”, adding that it is likely to become the next dominant strain.

Prof Grant projected Omicron’s R-value at between 2.75 and 4.4.

This compares with a current overall R-rate of between 0.9 and 1.1 in England, according to the Government’s latest figures.

Prof Grant added that as a worst case scenario, there may already be 2,500 Omicron cases in England, and that 2% of positive swabs taken on December 4 were likely to have been Omicron.

He said: “These numbers are very preliminary.

“They are likely to be overestimates as testing has focused on people at higher risk of infection because of their travel history or contact with confirmed Omicron cases.

“But it is very likely that Omicron will quickly come to dominate cases in England, and that overall case numbers will increase from their current levels.”

The R-rate is the average number of people that one infected person will pass a virus on to.

England’s latest overall R-number means that on average, every 10 people with coronavirus will infect between nine and 11 others.

A total of 440 Omicron cases had been confirmed in the UK as of Tuesday – 333 in England, 99 in Scotland, five in Wales and three in Northern Ireland.