LONDON-British Prime Minister Boris Johnson was taken to hospital on Sunday after failing to shake off coronavirus symptoms, as Queen Elizabeth II said a united effort would defeat the outbreak.

The government announced within an hour of the monarch’s rare special address to the country and Commonwealth nations that Johnson had been admitted for further tests as a precaution.

Johnson, 55, had been due to re-emerge from seven days of self-isolation on Friday, a week after announcing he had tested positive for COVID-19 and had mild symptoms.

But he said in a video message on Friday that he would continue to stay at home because of a persistent high temperature.

Downing Street called it a “precautionary step” and it is understood his admission was not an emergency and he was taken to hospital on medical advice. When he announced his positive test, his spokesman said Foreign Secretary Dominic Raab would take charge if the prime minister was unable to perform his duties.

But government sources said Johnson was still in charge. Johnson is the most high-profile world leader to contract the virus. His pregnant partner, Carrie Symonds, is also recovering from symptoms but has not been tested.

Health Secretary Matt Hancock returned to work on Friday after a week at home following his positive test for COVID-19. The chief medical officer, Chris Whitty, has also displayed symptoms. Hancock on Sunday described Johnson’s condition as “OK” and said he had been in “good spirits”.

“He’s very much got his hand on the tiller,” he told Sky News television but said Johnson was being careful to follow government advice on self-isolation.

Speaking from the White House, US President Donald Trump said he was “hopeful and sure” Johnson would recover, calling the prime minister “a friend of mine” and “great leader.”