Japan, Spain, France, Sweden and Canada have found small numbers of infections involving a new, potentially more transmissible variant of the coronavirus, most linked to travel from Britain, where it was first detected.
The rapid spread of the variant led to the lockdown of London and southern England this week, prompted a temporary French blockade of the English Channel and resulted in countries around the world barring travelers from Britain. Because few countries have the level of genomic surveillance that Britain does, there is concern that the variant may have been traveling across the world undetected for weeks.
A recent study by British scientists found no evidence that the variant is more deadly than others but estimated that it is 56 percent more contagious.
So far, the British variant has been diagnosed in seven people in Japan, the country’s health ministry said. All had either recently traveled to Britain or been in contact with someone who had.
The discovery in Japan prompted the country to close its borders to all new entry by nonresident foreigners. The ban will go into effect at midnight on Monday and last through the end of January, the public broadcaster NHK reported.
In Spain, the variant was found in the capital region, local authorities said on Saturday. Antonio Zapatero, a regional health official, said that four cases had been confirmed in Madrid, while another three were being treated as suspicious. At least two of the cases involve people who had recently been to Britain and then tested positive in Madrid, as well as some of their relatives.
The first case of the new fast-spreading variant of the coronavirus in France was identified on Friday, according to the French health ministry. Officials said that the patient was a French citizen living in Britain who had traveled from London to Tours, a city in central France, on Dec. 19, a day before the British government imposed a lockdown following the emergence of the variant.
Officials in Sweden announced on Saturday that a case of the variant had been detected there after a traveler visited Sormland, near Stockholm, from the United Kingdom over Christmas, Reuters reported. No additional cases had been detected, the Public Health Agency of Sweden said.
Health officials in Ontario, Canada, said on Saturday that they had confirmed two cases of the variant in the province. The two cases were a couple from Durham, about 90 miles northwest of Toronto. The couple had no known travel history, exposure or high-risk contacts, the province’s health ministry said.
It is normal for viruses to mutate, and most of the mutations of the coronavirus have proved minor. The British variant has a constellation of 23 mutations, several of which might alter its transmissibility. Vaccine experts are confident that the available vaccines will be able to block the new variant, although that has to be confirmed by laboratory experiments that are now underway.
The European Union’s member nations are scheduled to begin vaccinating against the virus on Sunday with the Pfizer-BioNTech vaccine. Hungary began administering the vaccine a day early, on Saturday.
A few other concerning variants have also been identified, including one in South Africa and another in Nigeria. Britain said on Thursday that it would ban travel from South Africa after the British health secretary, Matt Hancock, said two people were confirmed to have been infected with the variant that emerged there.
Germany, the Netherlands, Lebanon, Australia and Singapore have identified infections with the new variant. And Denmark, which has wider genomic surveillance than many other countries, detected 33 cases of the variant from Nov. 14 to Dec. 14, according to the Danish health authorities.
The U.S. has not yet reported any cases of the U.K. variant. But the country will require all airline passengers arriving from Britain to test negative for the coronavirus within 72 hours of their departure, the Centers for Disease Control and Prevention said Thursday. The rule will take effect on Monday.
Hisako Ueno and Mike Ives contributed reporting.