UK imposes new lockdowns to curb new Covid-19 strain

The new lockdown means many families are not allowed to get together for Christmas. Mr. Johnson, commenting just days ago that it would be “inhumane” to curtail the Christmas celebration, said, “I have to tell you with a heavy heart that we cannot go ahead with Christmas as planned.”

The new restrictions apply to the capital, as well as much of South East and East England. In London, the new strain of the virus accounted for 62% of new cases identified in the week through Wednesday.

Similar steps have been taken across Europe to curb rising caseloads. In Italy, Prime Minister Giuseppe Conte announced a total country-wide lockdown on Friday for the first time since May, which will be in effect over Christmas, from December 24 to January 6.

In the London area, non-essential stores must close and people must stay home from midnight on Saturday, with limited exceptions for some types of work and essential groceries, Mr Johnson said. Places of worship remain open.

Households are not allowed to mingle at Christmas and people are not allowed to visit other regions, in an effort to prevent the species from being sown elsewhere in the country.

“If the virus changes its attack method, we have to change our defense method,” said Mr. Johnson.

In the rest of England, Scotland and Wales, households are only allowed to mix on Christmas Day, rather than for a five-day period previously announced by the government.

The country reported 27,052 new daily infections on Saturday, bringing the total number of known cases in Britain to more than 2 million. There are currently nearly 19,000 people in hospital with Covid-19, and the country has reported an average of more than 400 deaths a day for the past seven days.

The UK became the first Western country to vaccinate people with a clinically approved vaccine earlier this month. Mr. Johnson said 350,000 people had now been shot. That compared to more than 137,000 on December 15.

The country reported its discovery of the new species on Monday and has already notified the World Health Organization.

Scientists have identified about 23 differences in genetic material with established strains. Those include changes in areas known to be related to how the virus binds and enters cells, which could explain why it is spreading faster, said Patrick Vallance, the UK government’s chief scientific adviser.

He said it has already become the dominant species in parts of England and is displacing older varieties. “This virus is on the rise, it moves quickly and it inevitably leads to a surge in hospital admissions,” he said.

Scientists also said the increased transmissibility of the strain could increase the R number – or the number of people who, on average, infect each person with the infection – by 0.4 or more. The latest estimate of R in the UK is 1.1 to 1.2.

British officials said it’s not clear where the variant emerged – although it may have been in the southeastern country of Kent, which borders London – or whether it is present abroad. They said its virulence might explain why the restrictions that were effective in lowering cases in other parts of the country had not done so in Kent.

They said precautions to slow the spread of the virus, such as staying six feet away from people, wearing a face mask, and washing hands often, should be followed.

Viruses multiply rapidly and mutations often occur due to tiny mistakes in copying genetic material, which can build up over time, creating new variants that behave slightly differently than older species.

Scientists around the world have been tracking these genetic changes since the start of the pandemic. More than 1,000 variants of the virus that causes Covid-19 have been detected so far.

The new variety is not the first time that a more transferable strain has emerged. Scientists described a variant in July that has over time displaced an older strain of the coronavirus to become the dominant strain in the global pandemic. Experiments showed that variant, known as G614, replicated faster, but appeared just as sensitive to antibodies targeting the previous strain and was not associated with more serious disease.

Much of the new wave of Europe over the summer, meanwhile, could be traced back to outbreaks among farm workers living in cramped conditions in the Spanish regions of Catalonia and Aragón. Researchers from Switzerland and Spain have identified a variant known as 20A.EU1 that spread from there by returning tourists to nearby cities and across Europe.

In Italy, where the government reported 674 deaths from Covid-19 on Friday, the areas most affected are the northern regions of Lombardy, Veneto and Piemonte. But the southern region of Campania, which also includes the city of Naples, is now one of the five most affected regions.

A maximum of two guests are allowed in each house in Italy during this time, but the limit does not apply to children under 14 years of age. Bars, restaurants and non-essential businesses are closed. Curfews in effect from 10 PM to 5 AM will continue to apply.

Unlike during the Spring Rise in Italy, churches will remain open, albeit with limited capacity, depending on social distance.

Elsewhere in Europe, Germany and the Netherlands have imposed lockdowns until Christmas, and Austria said on Friday that non-essential businesses will be shut down from December 26.

—Francis X. Rocca in Rome contributed to this article.

Write to Jason Douglas at [email protected]