FILE - Prime Minister Boris Johnson (seen wearing a face mask with a number 10 embroidered into it) attends a service to mark the centenary of the burial of the Unknown Warrior at Westminster Abbey on November 11, 2020 in London, England. (Max Mumby/Indigo/Getty Images/Pool)LONDON - British Prime Minister Boris Johnson is self-isolating after being told he came into contact with someone who tested positive for the coronavirus, officials said Sunday.“He will carry on working from Downing Street, including on leading the government’s response to the coronavirus pandemic,” a statement from his office said.Johnson “is well and does not have any symptoms of COVID-19,” it added.RELATED: UK at 'tipping point:' England braces for more COVID-19.