Boris Johnson will likely undergo several tests on his organs and breathing after he was admitted to hospital on Sunday night, doctors have said.

The prime minister, 55, is receiving treatment 10 days after he tested positive for COVID-19.

He will stay for as long as needed in the London NHS hospital where he was taken as a precautionary step on the advice of his doctor – rather than as an emergency.

His symptoms which have been described as persistent are understood to include a high temperature.

While in hospital, doctors will likely check the prime minister’s oxygen levels, white blood cell count, and liver and kidney function before he is released.

Dr Simon Clarke, a microbiologist from University of Reading, told Sky News: They will look at his general physiology and biochemistry, make sure his organs are functioning properly and that he can breathe okay.

I imagine these are fairly routine checks just to make sure he’s alright.

Dr Clarke added: You would normally expect him to get over it quicker but there are instances where people who are fit and healthy and not over the 70 isolation threshold who do struggle a bit – and we don’t really know why.

It’s a bit like why we don’t understand why some people don’t get symptoms at all or don’t get infected at all.

Some people may take a bit longer to recover following the typical seven-day quarantine period, Dr Clarke explained.

GP Dr Ellie Cannon told Sky News that still being ill at 10 days is probably a red flag if he still has symptoms, adding: Until you are fully better you are not out of the woods.

Health Secretary Matt Hancock, who tested positive for coronavirus at the same time as Mr Johnson, has since recovered.

Dr Bharat Pankhania, senior clinical lecturer at University of Exeter Medical School, said the prime minister’s doctors would be playing it safe since pneumonia can take hold very quickly.

He said: If a patient is developing pneumonia, it can get progressively worse very quickly and hence early admission upon the first signs of difficulty with breathing are very important.

Researchers in China found that 80% of people who catch coronavirus will only get mild symptoms and recover.

Some 87% of more than 80,000 infected people have recovered from COVID-19 in China and more than 3,200 have died.

In the UK, it was revealed on Sunday that another 621 hospital patients died after contracting coronavirus – taking the UK’s total to 4,934.

The number who have tested positive across the UK now stands at 47,806.

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Mr Johnson has been self-isolating in 11 Downing Street in a residence above the chancellor’s office since testing positive for the virus.

His pregnant partner, Carrie Symonds, announced on Saturday she had spent a week in bed with coronavirus symptoms but struck an optimistic tone, saying: I haven’t needed to be tested and, after seven days of rest, I feel stronger and I’m on the mend.

(c) Sky News 2020: Coronavirus: What hospital tests will Boris Johnson have as he battles COVID-19?