Kim Hjelmgaard | USA TODAY

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LONDON – British Prime Minister Boris Johnson on Friday became the first major world leader to test positive for coronavirus.

Johnson confirmed the infection on his official Twitter account.

His health minister, Matt Hancock, also tested positive.

Britain's leader, 55, said he developed mild symptoms over the last 24 hours, but that he would continue to lead and coordinate the country's response to the outbreak.

"I am now self-isolating, but I will continue to lead the government’s response via video-conference as we fight this virus," he said.

"But be in no doubt that I can continue, thanks to the wizardry of modern technology, to communicate with all my top team to lead the national fightback against coronavirus."

Hancock's symptoms are also mild. He is 41 and said he would work from home.

Johnson's fiancée Carrie Symonds, 32, is seven months pregnant.

A numbers of world leaders, including President Donald Trump and Brazil's President Jair Bolsonaro, have been tested for coronavirus recently after coming into contact with officials and advisers who caught the disease.

German Chancellor Angela Merkel has been in isolation since her doctor tested positive for the virus, but her first two tests have been negative.

Four U.S. lawmakers – three from the House of Representatives and one from the Senate – have tested positive. They are: Rep. Mario Diaz-Balart, R-Fla., Rep. Ben McAdams, D-Utah, Rep. Joe Cunningham, D-SC, and Sen. Rand Paul, R-Ky.

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Johnson has been chairing daily emergency coronavirus meetings with Hancock and Britain's treasury minister Rishi Sunak as well as holding daily online briefings with the media. During the media briefings, Johnson has appeared in person alongside the country's top scientific and medical advisers.

Earlier this month, Prince Albert II of Monaco became the first reigning monarch or head of state to publicly announce a diagnosis for the respiratory disease. But Johnson is the most high-profile leader to have contracted the virus.

"The way we will get through it is of course by applying the measures that you have heard so much about," Johnson said in his video statement, referring to measures he's taken to stem the outbreak's spread. These have effectively closed down much of the British economy and introduced strict curbs on people's day-to-day movements.

Britain's leader last appeared in public Thursday night outside his official residence and office at No. 10 Downing Street as he joined a nationwide gesture to thank members of Britain's National Health Service combating the virus by clapping for around a minute.

In a statement, the White House said that President Donald Trump spoke with Johnson on the phone and "wished him a speedy recovery."

If Johnson becomes too ill to run the country, under British protocol his Foreign Secretary Dominic Raab would temporarily lead the government.

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On Wednesday, Prince Charles, 71 – heir to the British throne – tested positive for coronavirus. He, too, is displaying mild symptoms, according to a royal spokesman.

Britain has almost 15,000 confirmed coronavirus cases and about 800 deaths. Johnson last came into contact with Queen Elizabeth, the country's 93-year-old monarch on March 11. Her son, Prince Charles, last saw his mother briefly a day later.

Overnight, the number of infections in the U.S. surpassed China's.

The U.S. has about 86,000 coronavirus infections compared to China's 82,000. Around 1,300 people have died in the U.S.; 3,300 in China.

But some political scientists urged caution over the numbers.

"China numbers can’t be trusted because the government lies," said Ian Bremmer, president of the New York-based Euraisa Group think tank, in a tweet. "U.S. numbers can’t be trusted because the government can’t produce enough tests."

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