U.K. Prime Minister Boris Johnson was admitted to the hospital on Sunday night. On Monday, Johnson was sent to intensive care with severe symptoms of coronavirus (COVID-19). 

A Downing Street spokeswoman said in a statement that the hospitalization was precautionary and had taken place “on the advice of his doctor.”

“This is a precautionary step, as the prime minister continues to have persistent symptoms of coronavirus ten days after testing positive for the virus,” the spokesperson said. Downing Street did not say which hospital the prime minister was admitted to.

Johnson had confirmed he had the coronavirus last Friday and had been in isolation since. Johnson remains in charge of the government. Foreign Secretary Dominic Raab has been nominated as the “designated survivor” in case Johnson becomes incapacitated. 

Johnson’s hospitalization came just an hour after Queen Elizabeth II gave a television address to the nation. In the speech, the queen called for national unity in “increasingly challenging time.”

U.K. Health Secretary Matt Hancock, who also tested positive for the virus but has recovered, told Sky News that Johnson was doing fine. “He has still got a temperature … I was lucky, I had two pretty rough days and then I bounced back and some people do get it pretty mildly, and then for others, it’s very, very serious and the prime minister is not at that end of the spectrum.”

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President Donald Trump wished the prime minister well at the beginning of his Sunday press conference. “I want to stress our nation’s well wishes to Prime Minister Boris Johnson as he wages his own personal fight with the virus,” Trump said. “All Americans are praying for him.”