In a bid to combat the Omicron variant, the government announced travellers to the UK will be required to take pre-departure Covid-19 tests. It also made masks mandatory in shops and public transport this week.
Deputy Prime Minister Dominic Raab declared everyone will be able enjoy Christmas this year despite the restrictions.
But Professor Sir David Spiegelhalter has warned the UK will be moving into “one of the highest risk periods” over the coming weeks due to large amounts of indoor socialising during the festive season.
He told Sky News: “The travel restrictions are only going to slow things down a little, they’re not going to stop it.
“In the New Year we’re likely to see a lot of challenges and that could mean more stringent measures.”
Omicron has sparked alarm among scientists over its contagiousness and potential to evade vaccines.
The total number of confirmed cases in England is now 246.
But Spiegelhalter, a statistician at the University of Cambridge, said symptoms do not appear to be severe based on current evidence.
"It doesn’t look as if it’s really severe if you get it," he said. "I think that’s about all we can say at the moment."
He also praised the booster vaccines for "saving very large numbers of lives".
"It’s a very strange situation we’re in where cases in young people are going up, but cases in old people are coming down," he said.
"That’s the booster effect - we are being saved by boosters essentially - they are extraordinarily effective."
He warned the public will have to get booster shots for the “foreseeable future”.
It comes after the Government announced that travellers to the UK will be required to take pre-departure Covid-19 tests.
The new measure, to limit the spread of the Omicron variant, applies to everyone visiting the UK or returning from a holiday, regardless of vaccination status.
It will come into effect from from 4am on Tuesday December 7.
Nigeria is also being added to the travel red list - joining several southern African nations which were added after the Omicron variant was first detected late last month.