British Prime Minister Boris Johnson was in stable condition Tuesday in a hospital intensive care unit with the coronavirus, and while he is not on a ventilator, he is receiving oxygen, his spokesman said.

Foreign Secretary Dominic Raab has taken over many of Johnson’s duties temporarily while he is being treated at St. Thomas’ Hospital. Britain has no official post of deputy prime minister.

The 55-year-old Johnson is the first major world leader to be confirmed to have COVID-19. He was admitted to the hospital late Sunday with a fever and cough that persisted 10 days after he was diagnosed with the virus. He was moved to the ICU Monday evening after his condition worsened.