Meanwhile, Princess Alexandra Hospital in Harlow confirmed Lynsay Coventry, 54, who died on Thursday, was the first serving midwife to die after testing positive for the virus.
The former Prime Minister said he did not want to criticise the Government but to offer critical advice.
The Guardian leads with Mr Johnson alongside a story on the Queen's "message of hope" to the nation.
Conservative MP Andrea Leadsom tweeted: "Praying for a speedy recovery for our Prime Minister".
Her social media post on her own symptoms subsiding came as Johnson, 55, continues to self-isolate at Downing Street after testing positive for coronavirus last week.
The prime minister, alongside the Queen, personifies the country's public response to this pandemic.
Dr Jarvis, who is not Johnson's doctor, added: "Given he is staying in charge of the Government, that suggests to me that he probably has moderate disease but that, as a precaution, he is being taken in to check the oxygen levels in his blood, to do X-rays and probably scans of his chest".
The coronavirus has repeatedly proven its capacity to turn the far-fetched into reality, over and over again.
"We will succeed - and that success will belong to every one of us", she said in a speech recorded at Windsor Castle, west of London, where she moved as a precaution on March 19.
Dr Sarah Jarvis, a GP and broadcaster, told the BBC that Mr Johnson would be likely to have his chest X-rayed and his lungs scanned, particularly if he had been struggling for breath. He has been working from home for the past 10 days, most recently chairing a meeting via video conference on Friday. They simply followed the government's mandate, later corrected, which forced all those who lived with someone who had symptoms of the coronavirus to remain in isolation for 14 days.
"I still have a temperature and so, in accordance with government advice, I must continue my self-isolation until that symptom itself goes".