Millions of people across southeast England will no longer be able to mix with other households at Christmas, as a stricter level of COVID restrictions – equivalent to a full lockdown – comes into force.

In a dramatic move, prompted by fears over a new strain of coronavirus, all those areas currently in Tier 3 in the South East – including London – will move to the new Tier 4 on Sunday.

Tier 4 requires all non-essential shops, hairdressers and indoor leisure venues to close after the end of business hours. People will have to stay home apart from limited exceptions such as work – if people cannot work from home – education, childcare and exercise.

With just five days to go until Christmas, Johnson also announced that a planned easing of socializing rules that would have allowed up to three households to meet in “Christmas bubbles” from Dec. 23 to Dec. 27, will be canceled for Tier 4 areas and sharply curtailed in the rest of England.

The number of cases in England has soared in the last two weeks because of a variant of the virus that scientists said is up to 70% more transmissible. Johnson said the government had to take urgent action.

“It is with a very heavy heart that I must tell you we cannot proceed with Christmas as planned,” Johnson said.

He said he concluded there was “no alternative open to me” and people must sacrifice this Christmas to have a better chance of protecting the lives of loved ones.

“I know how much emotion people invest in this time of year, and how important it is for grandparents to see their grandchildren,” Johnson said. “But when the virus changes its method of attack, we must change our method of defense.”

Johnson said there’s no evidence to suggest the new variant is “more lethal or causes more severe illness, or that vaccines will be less effective against it.”

Wales also announced on Saturday it was bringing forward plans for a new national lockdown which would come into affect from midnight, whilst Scotland will also close its borders with other UK nations to try and stop the spread of the new variant of coronavirus.

England’s chief medical officer, Chris Whitty, said the UK has alerted the World Health Organization that the new variant identified this week appears to be accelerating the spread of COVID-19. The government’s scientific advisers came to that conclusion based on preliminary modelling figures, and they are continuing to analyze the available data, he said.

Britain has been one of the worst hit European countries – with more than 67,000 deaths linked to coronavirus and more than 2 million cases reported.