Donald Trump and Angela Merkel had false alarms, but Boris Johnson becomes the first Western leader to contract COVID-19. Johnson became mildly symptomatic with a mild fever and cough, Johnson announced on Twitter, and took the coronavirus test on the advice of his physician. Now that he has confirmed his infection, the PM tells his UK constituents that he will carry out his duties from Number 10 in self-isolation, and emphasizes the need to follow stay-at-home policies:

Over the last 24 hours I have developed mild symptoms and tested positive for coronavirus.

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

Together we will beat this. #StayHomeSaveLives pic.twitter.com/9Te6aFP0Ri

— Boris Johnson (@BorisJohnson) March 27, 2020

Mr Johnson said he developed mild symptoms over the past 24 hours, including a temperature and cough.

He said he will now self-isolate in No 10 but will “continue to lead the government’s response via video-conference as we fight this virus”.

Mr Johnson was last seen on Thursday night, as he clapped outside No 10 as part of a nationwide gesture to thank NHS staff.

In a video on his Twitter account, Mr Johnson said: “I’m working from home and self-isolating and that’s entirely the right thing to do.

“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.

“I want to thank everybody involved and, of course, our amazing NHS staff.”

USA Today reports that Johnson is the first “major” world leader to test positive, but that may or may not be true. The pandemic has ravaged Iran and has killed at least one high-ranking official there who had access to president Hassan Rouhani, who himself has access to supreme leader Ali Khameini. Both of those leaders have not been seen much lately, and any test they may have taken probably wouldn’t be made public — especially if it came back positive. It is more accurate to say that Johnson’s the first major world leader to acknowledge that diagnosis.

What’s the contingency plan if the 55-year-old PM gets too sick to function? USA Today explains, and points out that this is yet another potential vector to the monarchy:

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 combatting the virus by clapping for around a minute.

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

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 12,000 confirmed coronavirus cases and about 600 deaths. It is not immediately clear when Johnson last came into contact with Queen Elizabeth, the country’s 93-year-old monarch. Prince Charles last saw her briefly on March 12.

Buckingham Palace later clarified:

JUST IN: Queen Elizabeth last saw Boris Johnson March 11 and is following all appropriate advice with regards to her welfare, Buckingham Palace says pic.twitter.com/HQbhaPFK9K

— Reuters (@Reuters) March 27, 2020

The announcement that Johnson has contracted COVID-19 might sober up some people who thought the disease might already be abating. Statistically speaking, Johnson’s much more likely to have a mild flu-like bout than anything worse, but it’s not as if nothing worse is going on. Spain announced a new spike in deaths earlier this morning, with 769 COVID-19 deaths in the past 24 hours, a new record in that country. Hungary just announced a nationwide two-week lockdown, too, a sign that the situation remains dire in Europe, where social-distancing policies came late in the spread cycle.

Update: This doesn’t bode well:

#BREAKING British Health Secretary Matt Hancock tests positive for COVID-19 after PM Johnson pic.twitter.com/58coX3D4Fp

— AFP News Agency (@AFP) March 27, 2020

Hancock’s responsibilities include the NHS, Britain’s single-payer health care system.