Scientists from the London School of Hygiene and Tropical Medicine (LSHTM) have warned that the UK will face a substantial wave of Omicron infections without further restrictions beyond the Plan B measures announced last week.
If it's half as severe as Delta and 1% of severe infections need hospitalisation that's 10,000 people with the first million and it keeps going that way," he told BBC One's Andrew Marr Show.
Dr Susan Hopkins, head of the UK Health Security Agency, said that she expected to see an increase in the number of people in hospital with Omicron infection.
It is "inevitable" that there was going to be a big wave of infections but what was not clear was the impact that would have on hospitals, she said.
She said the sheer weight of numbers of people being infected with Omicron means it will find the unvaccinated or people who have had a poor immune response to the vaccine.
"This is a big wave coming straight at us - if we see even half the severity that we saw with Delta then we are facing a very large number of hospitalisations and potential deaths," she said.