The British Prime Minister Boris Johnson has tested positive for coronavirus, becoming the first head of state to confirm they have been infected.

“After experiencing mild symptoms yesterday the prime minister was tested for coronavirus on the personal advice of England’s Chief Medical Officer Professor Chris Whitty,” a Downing Street statement said Friday morning.

Johnson is now self-isolating in the chancellor’s residence at No. 11 Downing Street and is “continuing to lead the government’s response to coronavirus.”

In a video posted on Twitter, Johnson said that in recent days he’d “developed mild symptoms of the corona virus that’s to say, a temperature and a persistent cough” before being tested.

“Thanks to the wizardry of modern technology to communicate with all my top team to lead the national fight back against coronavirus,” Johnson said.

Johnson, whose fiancee Carrie Symonds is pregnant,, was last seen in public on Thursday evening outside Downing Street, where he clapped as part of a nationwide campaign to thank the frontline staff of the U.K.’s health service.

Several staff at No. 10 will now also have to self-isolate, according to the Sun, while Chancellor Rishi Sunak says he will not be self-isolating despite spending considerable time with Johnson this week.

Johnson will be in isolation for seven days but it’s unclear if he will still be living with Symonds.

He said that self-isolation and social distancing were the best way for the country to stop the spread of the virus. “The more effectively we all comply with those measures, the faster our country will come through this epidemic and the faster we will bounce back,” Johnson said.

Johnson was criticized earlier this month for saying he was “shaking hands with everyone” at a time when the coronavirus was beginning to take hold in the U.K. At the time, Johnson’s administration was advocating a “herd immunity” approach to tackling the pandemic, something the government has since abandoned in favor of self-isolation and social distancing.

The U.K. has over 11,600 confirmed cases of coronavirus so far, and 578 deaths.

It was announced earlier this week that if Johnson were to become unwell, First Secretary of State Dominic Raab would stand in as acting prime minister.

A number of political figures have already wished Johnson a speedy recovery, including Charles Michel, the head of the European Council, and London Mayor Sadiq Khan.

Johnson is the first head of state to confirm he has contracted coronavirus, but not the first major UK figure: on Wednesday, it was announced that Prince Charles was also infected. German Chancellor Angela Merkel and Canadian Prime Minister Justin Trudeau are also in self-isolation, though neither has tested positive for coronavirus so far.

Cover: British Prime Minister Boris Johnson outlines his government’s negotiating stance with the European Union after Brexit, during a key speech at the Old Naval College in Greenwich, London, Monday, Feb. 3, 2020. (AP Photo/Frank Augstein, Pool)