UK’s Prime Minister Boris Johnson has tested positive for COVID-19 coronavirus, the PM announced on his Twitter account Friday.

Johnson, 55 years old, says he developed mild symptoms over the past 24 hours and is under self-isolation in his residence on Downing Street 10. He will still be leading the government’s response to the coronavirus outbreak in the country.

The latest figures put the number of confirmed COVID-19 cases in the UK at 11,658, with 578 deaths. 

Responding to the surging infections, UK authorities went for a nation-wide lockdown, with non-essential businesses shut and residents ordered to not stay outside for more than one hour.

Johnson is the first Western state leader confirmed to have contracted the coronavirus, with Brazil’s President Jair Bolsonaro earlier refuting reports that he tested positive.

US President Donald Trump and Vice President Mike Pence earlier took coronavirus tests after contacts with Bolsonaro’s communications chief, who tested positive, and both tests returned negative.