Boris Johnson has not set out a timetable to return to work as he continues his recovery at Chequers.
The Prime Minister spoke to Dominic Raab over the weekend, but is "focused on his recovery" and is not carrying out government work.
Mr Johnson's spokesman said: "The Prime Minister has been discharged to continue his recovery as Chequers and would not be returning to work immediately on the advice of his medical team."
It means Dominic Raab will continue to deputise for the PM on key issues until he returns to government.
The Prime Minister's official spokesman said that confirmed that Mr Johnson tested negative for Covid-19 on leaving hospital.
Mr Johnson's spokesman said: "I'm told it is standard practice in hospital to do that. And the results came back negative."
Asked why he was at Chequers and not his primary residence at No 10, the spokesman said: "it is considered to be a suitable place for the PM to continue his recovery".
Asked about how long Mr Johnson's recovery could his spokesman said he didn't have a date and would not speculate - but it would be led by the medical advice.
Pressed on how ill the PM was, Mr Johnson's spokesman said: "As we set out, his condition did worsen over the course of last Monday afternoon and he had to be moved to the intensive care unit.
"Now, clearly, if a person is moved to intensive care, that means that they are requiring a significant level of specialist treatment.
"So, I think it was clear from the moment the Prime Minister was moved to intensive care that his condition had worsened."
It comes after Mr Johnson paid tribute to the NHS as he was discharged, saying there is "no question" it saved his life after he contracted coronavirus.
The Prime Minister, speaking in a video released shortly after he was discharged from hospital, admitted there was a 48-hour period when things "could have gone either way".
Speaking in the video message posted online Mr Johnson thanked the "utterly brilliant" doctors, and praised the nurses for their "astonishing" care.
He said the NHS would be "unconquerable" in the face of the coronavirus pandemic.
He said: "I have today left hospital after a week in which the NHS has saved my life, no question.
"It's hard to find the words to express my debt - but before I come to that, I want to thank everyone in the entire UK for the effort and the sacrifice you have made and are making."
He thanked people for continuing to socially distance and to self-isolate, saying: "I do believe that your efforts are worth it, and are daily proving their worth."
While he said the "the struggle is by no means over", he appeared to offer some hope by adding that progress is being made.
He said: "We are making progress in this national battle because the British public formed a human shield around this country's greatest national asset - our National Health Service."
Mr Johnson said he had personally "seen the pressure the NHS is under" and listed the essential staff including cleaners, cooks and all healthcare workers who he said had shown "personal courage" by continuing to work and "risking this deadly virus".
He said: "It is thanks to that courage, that devotion, that duty and that love that our NHS has been unbeatable."
