Scientists have crunched coronavirus statistics to reveal the fatality rate for infected patients with underlying health problems.

Data shows patients with pre-existing conditions are more likely to suffer severe illness and die because their immune systems are weaker.

Researchers in China, who studied more than 72,000 patients, found 10.5 per cent of heart disease sufferers who became ill with COVID-19 died.

The fatality rate was 7.3 per cent for diabetics and 6.3 per cent among people with chronic respiratory diseases, such as asthma.

The World Health Organization has recently advised vulnerable people to be extra vigilant and avoid crowded areas, or anywhere they could come into contact with sick people.

Cases have reached almost 800 in the UK, and ten people have died. But officials yesterday revealed up to 10,000 patients could already be infected.

Boris Johnson warned ‘many more will die’ of the coronavirus in the UK, but just how many remains to be seen.

Scientists have crunched coronavirus numbers to reveal the fatality rate for those with underlying health problems. Data from China shows 10.5 per cent of heart disease patients who became ill with COVID-19 did not survive, compared to 0.9 per cent of healthy people

The study did not break the data down into age brackets or gender for each condition. Therefore it is not known, for example, how a 55-year-old man with high blood pressure would fare compared with a 65-year-old woman with diabetes.

The killer virus sweeping the globe can infect anybody, but those with more severe illness and those who ultimately die tend to be elderly or suffer from another underlying illness.

WHAT IS THE MORTALITY RATE? Conditions Heart disease: 10.5% Diabetes: 7.3% Chronic respiratory disease: 6.3% High blood pressure: 6% Cancer: 5.6% None: 0.9% Ages 0-9 years: N/A 10-19 years: 0.2% 20-29 years: 0.2% 30-39 years: 0.2% 40-49 years: 0.4% 50-59 years: 1.3% 60-69 years: 3.6% 70-79 years: 8% Over 80 years: 14.8%

People with compromised health aren’t immediately guaranteed to become seriously unwell, they are just at a higher risk.

Doctors and families have also reported deaths in people who were seemingly completely healthy before being infected.

Chinese Centre for Disease Control and Prevention researchers looked at 72,314 confirmed, suspected, clinically diagnosed, and asymptomatic cases of COVID-19 illness across China as of February 11.

Results showed the overall case-fatality ratio – the percentage of patients who die – was just 2.3 per cent.

But this jumps higher in those with underlying conditions and the elderly, according to the findings in the Chinese Journal of Epidemiology.

Those with heart disease fared worse – one in ten people studied died. This was followed by diabetics, who had a 7.3 per cent fatality rate (one in 13.6 people).

Of those with chronic respiratory illnesses, one in 15.8 people died. Six per cent of people with high blood pressure (one in 16.6 people) died.

The group with any form of cancer had a mortality rate of 5.6 per cent.

Although COVID-19 is a respiratory disease that primarily affects the lungs, the body comes under enormous stress while trying to fight back.

Those who have underlying conditions to begin with ‘have less of a “safety net” to cope with the demands’, Professor Naveed Sattar, an honorary consultant in cardiovascular and medical sciences, explained.

He told MailOnline: ‘If you are healthy, your buffer capacity is good. The rest of your body can cope with the stress.

‘But if you have impairments to begin with, your systems break down.’

In many patients with COVID-19, the lungs are unable to receive enough oxygen. This has a knock-on effect on other organs.

Professor Sattar, at the University of Glasgow, explained the heart comes under a lot of strain trying to pump oxygenated blood around the body, including to the brain.

Dr Hajira Dambha-Miller, a GP and clinical lecturer, said the blood is less able to circulate in people who have high blood pressure because their vessels are narrower.

Not only does this slow the route of oxygen to organs, but it also means immune cells in the blood are not able to reach the virus as quickly as needed.

‘If you’ve got diabetes’, she said, ‘you have high sugar levels and your blood becomes like treacle.

‘Physically, its harder for the immune system to get to the virus. The virus bugs do a lot of damage before the immune system even realises it’s there.

‘When the body does kick in, it won’t work as it should do. The immune cells are damaged because they’ve been saturated in sugar for years and don’t work the way they should.’

Dr Damnha-Miller said similar processes are impaired in the elderly.

A separate group of virologists studying the coronavirus have also claimed it is up to 20 times more infectious than its sister SARS. But SARS is deadlier with a mortality rate of 10 per cent.

Chinese Centre for Disease Control and Prevention researchers also found 80.9 per cent of infections are mild.

Less than five per cent are critical and needing hospital care.