LONDON — British Prime Minister Boris Johnson, who was diagnosed with the new coronavirus more than a week ago, was admitted to a hospital Sunday for tests.

Johnson’s office said he was hospitalized because he still has symptoms 10 days after testing positive for the virus. His admission to an undisclosed hospital in London wasn’t an emergency.

Downing St. said it was a “precautionary step” and Johnson remains in charge of the government.

Johnson, 55, has been quarantined in his Downing St. residence since being diagnosed with COVID-19 on March 26.

Johnson has continued to chair daily meetings on Britain’s response to the outbreak, and has released several video messages during his 10 days in isolation.

In a message on Friday, he said he was feeling better but still had a fever.

The virus causes mild to moderate symptoms in most people, but for some, especially older adults and the infirm, it can cause pneumonia and lead to death.

Johnson has received medical advice by phone during his illness, but going to a hospital means doctors can see him in person.

Johnson’s fiancee Carrie Symonds, 32, revealed Saturday that she spent a week with coronavirus symptoms, though she wasn’t tested.