* Being obese triples risk of hospital admission - CDC* Trump appears otherwise healthy and reasonably active
* Models put notional risk of dying at around 4%
US President Donald Trump's gender, age and weight are all factors that make him more vulnerable to developing severe Covid-19, and give him a notional risk of around 4% of dying from it, health experts said on Friday.
The probability is hard to assess precisely, however, since factors such as overall fitness and activity levels, pre-existing conditions and recent medical research can all make a significant difference.
A working paper by the US National Bureau of Economic Research published in July put an infected but otherwise healthy 70- to 79-year-old's risk of dying from Covid-19 at 4.6%, regardless of gender.
David Spiegelhalter, a professor of risk and an expert in statistics at Britain's Cambridge University, cited a Covid-19 survival calculator that put the mortality rate for an otherwise healthy 74-year-old white man with Covid-19 during the peak of the pandemic in Britain earlier this year at 3% to 4%.
That risk would now "presumably be somewhat less", he said, as doctors around the world have gained experience in treating the disease.
Michael Head, a global health professor at Britain's University of Southampton, said that "the president's profile would classify him as vulnerable. He is aged 74, and reportedly overweight".
Information provided by a White House physician in June puts the 74-year-old president in the obese category, which triples his risk of needing hospital treatment, according to data from the US Centers for Disease Control and Prevention (CDC) released in August.
Even for otherwise healthy 65- to 74-year-olds infected with coronavirus, the mortality risk is 90 times higher than for those aged 18-29, according to the CDC data.
Julian Tang, an expert in respiratory sciences at Leicester University, said that, apart from age and obesity, "other existing medical conditions like diabetes, hypertension, other chronic heart and lung disease can lead to serious Covid-19 disease".
But Naveed Sattar, a professor of metabolic medicine at the University of Glasgow, noted that Trump has no reported chronic conditions and is reasonably active - he plays golf frequently and appears to walk briskly - which may offset some of the risks.
The CDC data also do not take into account the state-of-the-art care that the president is likely to receive, although medical experts warned Trump's doctors not to be tempted to treat him differently from any similar patient.
"I would advise them: Do not deviate from your standard protocol - because that's when mistakes happen and you're starting to experiment," said Bharat Pankhania, senior clinical lecturer at Britain's University of Exeter Medical School.
"This is not a time or place to experiment, just because he happens to be the president."
A number of possible Covid-19 treatment approaches are currently being tested in late-stage trials, including manufactured antibodies designed to stop the coronavirus from invading cells.
Pankhania said the standard protocol would be to "monitor, and act if required".
"The usual thing that we need to act on, if required, is oxygen," he said. "And if a patient needs oxygen support, there may also be some benefit from giving the steroid dexamethasone."
The generic anti-inflammatory drug and Gilead's anti-viral remdesivir are the only drug therapies approved for treating hospitalised Covid-19 patients.