The PM took part in the clap for carers on Thursday outside No 11 Downing Street.
He was taken to a London medical facility on Sunday night with “relentless symptoms” – including a temperature.
Mr Johnson spent the night in medical facility and is having what have been explained as “routine tests”.
In a declaration, a Downing Street spokeswoman stated: “On the guidance of his doctor, the prime minister has actually tonight been admitted to healthcare facility for tests.
United States President Donald Trump started a White House press instruction by sending out “our nation’s well wishes” for Mr Johnson’s “own personal battle with the infection”.
” All Americans are praying for him. He’s a terrific friend of mine, a great gentleman and an excellent leader,” Mr Trump said, adding that he made certain the prime minister would be great due to the fact that he is “a strong p