Millions more people in England are entering the toughest coronavirus restrictions amid fears a new variant is accelerating the spread of the disease.
Boris Johnson was reported to have held an unscheduled meeting of ministers on Friday amid “growing concern” about the threat posed by the mutant strain – which is spreading fastest in South East England.
Professor Sir Mark Walport – a member of the Government’s Scientific Advisory Group for Emergencies (Sage) – said there was a real possibility that it could have a “transmission advantage”.
“What happens with viruses is they do naturally mutate all the time and the ones that are likely to do well are the ones that increase transmission,” he told BBC2’s Newsnight.
“Scientists are working extremely hard to work out what is going on. But it does definitely seem possible that this transmits more easily.
“It will make the social-distancing even more critical.”
Downing Street would not comment on reports that among the measures being considered by ministers were new travel restrictions for the South East of England.
However, the meeting comes as large parts of the region were following London and large parts of Essex and Hertfordshire, which entered the toughest Tier 3 restrictions earlier this week.
The NHS in Kent announced that it was suspending non-urgent hospital procedures as it was treating double the number of patients it had at the peak of the first wave in April.
With fears that the relaxing of the restrictions over Christmas could lead to a further upward spike, Mr Johnson on Friday refused to rule out the possibility of a third national lockdown for England in the new year.
“We’re hoping very much that we will be able to avoid anything like that. But the reality is that the rates of infection have increased very much in the last few weeks,” he told reporters during a visit to Bolton.
In Scotland, Health Secretary Jeane Freeman said the option for a post-Christmas lockdown “remains on the table”, while Northern Ireland and Wales are braced for fresh lockdowns following the festive period.
Sir Mark said the country was in a “serious situation” as it headed towards the new year.
“The infection numbers are very high indeed at the moment. It is rising quite rapidly in London, in the South East in the East of England,” he said.
“We are going into January in quite a serious situation where we do need quite strong measures to socially distance and if the virus is changing then that makes it even more imperative.”
The latest tiering changes in England – which came into force on Saturday morning at one minute past midnight – mean 38 million people are now living in Tier 3, 68% of the population of England.
Those areas moving into the highest tier are Bedfordshire, Buckinghamshire, Berkshire, Peterborough, the whole of Hertfordshire, Surrey with the exception of Waverley, Hastings and Rother on the Kent border of East Sussex, and Portsmouth, Gosport and Havant in Hampshire.
Elsewhere in the UK, Northern Ireland will see a six-week lockdown from December 26 to curb rising cases – with the closure of non-essential retail and contact services, as well as restricting the hospitality sector to takeaway only.
Wales will go into its third full lockdown from December 28 amid a “sustained rise in coronavirus”.