Part of England will spend the holidays confined.
Contamination figures have skyrocketed, which is believed to be due to a new strain of the new coronavirus.
"It appears that this spread is now being fueled by a new variant of the virus," which is transmitted "much more easily", the British Prime Minister said at a press conference.
"There is no indication that it is more fatal or that it causes a more severe form of the disease" or that it reduces the effectiveness of vaccines, he added, however.
Residents of the capital and the south-east of England are placed on the fourth alert level: the highest. They will be instructed to stay home, and non-essential businesses will no longer be able to reopen after lowering the curtain on Saturday, putting an end to last-minute Christmas shopping.
