LONDON 鈥 Prime Minister Boris Johnson imposed an effective lockdown on over 16 million people in England and reversed plans to ease curbs over Christmas, saying Britain was dealing with a new coronavirus strain up to 70% more transmissible than the original.

Although Mr. Johnson and his scientific advisors believe vaccines will still be effective, and the new strain is not more deadly or more serious in terms of the illness caused, he said on Saturday the government had to take urgent action.

The number of cases in England has soared in the last two weeks because of the virus variant.

Mr. Johnson tore up plans to allow three households to mix indoors for five days over the festive period, and said London and southeast England, which are currently in the highest level of a three-tier system of rules, would now be placed in a new Tier 4 level, similar to those of a recent national lockdown.

鈥淚t is with a very heavy heart I must tell you we cannot continue with Christmas as planned,鈥 Mr. Johnson told a news conference. 鈥淚 sincerely believe there is no alternative open to me.鈥

People in Tier 4 鈥 16.4 million and about a third of the population of England 鈥 will be required to stay at home except for essential reasons such as work, and non-essential retail will close, as will indoor leisure and entertainment.

Social mixing will be limited to meeting one other person in an outdoor space. The new rules will come into effect from midnight on Saturday.

Mr. Johnson, whose initial response to the pandemic has been criticized for being too slow, had resisted calls to change plans for the Christmas relaxation, saying on Wednesday it would be 鈥渇rankly inhuman鈥 to ban it.

However, those now in Tier 4 will not be allowed to mix with others over Christmas. And everyone else in England will now be allowed to see friends and family only on Christmas Day itself, Dec. 25.

鈥淎t this time of national crisis, the British people want clear, decisive leadership,鈥 opposition Labor leader Keir Starmer said on Twitter. 鈥淎ll we get from Boris Johnson is confusion and indecision.鈥

Within minutes of Mr. Johnson鈥檚 announcement, shoppers hit the streets for a final attempt to stock up on Christmas presents and supplies.

鈥淚t was fairly quiet all day, then suddenly there was this mass of people,鈥 said one sales assistant at a large department store at Westfield shopping centre in West London, one of Europe鈥檚 largest.

The UK鈥檚 other nations, whose response to the pandemic differs from that of England at times, also took action.

Scotland said on Saturday it would impose a ban on travel to the rest of the United Kingdom, and the Christmas easing would be limited to Dec. 25 only. All of Wales will go into Tier 4 from midnight, but two households can mix on Christmas Day.

Business leaders said the government needed to provide emergency financial support.

鈥淭he consequences of this decision will be severe,鈥 said Helen Dickinson, chief executive of the British Retail Consortium.

鈥楾AKEN OFF鈥
Like other countries in Europe, Britain is battling to contain new waves of the virus. It reported 27,052 new coronavirus disease 2019 (COVID-19) cases on Saturday, taking the total over 2 million, and 534 more deaths, taking the overall official toll to more than 67,000.

There has been a surge in infections sparked by the new virus strain 鈥 VUI202012/01.

鈥淭his virus has taken off, it鈥檚 moving fast and it鈥檚 leading inevitably to a sharp increase in hospital admissions,鈥 Britain鈥檚 Chief Scientific Officer Patrick Vallance said.

England鈥檚 Chief Medical Officer Chris Whitty said the authorities had alerted the World Health Organization (WHO) and were continuing to analyze the data.

鈥淭here鈥檚 no evidence to suggest it is more lethal or causes more severe illness,鈥 Mr. Johnson said. 鈥淭here鈥檚 no evidence to suggest the vaccine will be any less effective against the new variant.

Other countries have also reported variants of the virus. South Africa said on Friday one such strain was driving a second wave of infections there. 鈥 Reuters