A growing list of European Union nations barred travel from the U.K. on Sunday and others were considering similar action, in a bid to block a new strain of coronavirus sweeping across southern England from spreading to the continent. France, Germany, Italy, the Netherlands, Belgium, Austria, Ireland and Bulgaria all announced restrictions on U.K. travel, hours after British Prime Minister Boris Johnson announced that Christmas shopping and gatherings in southern England must be canceled because of rapidly spreading infections blamed on the new coronavirus variant.