Much of the focus on managing Australia's response to the coronavirus outbreak has been on protecting older Australians.

That makes sense, because the latest evidence suggests 13 per cent of people aged 80 or over who are infected with coronavirus will die — and 18 per cent will need to be hospitalised.

But Australians living with chronic illnesses may have a similarly elevated risk.

Anyone is at risk of catching coronavirus

The first column of the chart below, which comes from early data during the outbreak in China, shows that three quarters of the people infected with coronavirus had no chronic health conditions.

Around 13 per cent had high blood pressure, around 5 per cent had heart disease or chronic lung diseases and a tiny fraction had cancer.

That suggests that people with chronic health conditions were no more likely to get coronavirus than others.

Diana Rojas Alvarez, an infectious diseases epidemiologist from the college of public health at James Cook University, said everyone had the same risk of being infected because the virus was new.

"But once you get infected, the probability of getting symptoms and getting severe disease changes among the risk groups," she said.

But a person's risk of death goes up with chronic illness

The second column in the chart shows how likely each of the groups with chronic disease were to die from coronavirus infection.

The case fatality rate — that's the number of people who die as a proportion of the number infected — is changing as the pandemic unfolds, and is currently estimated to be 1.4 per cent overall.

The data showed that less than 1 per cent of people with no chronic health conditions died, but the death rates were above 10 per cent for those with a heart condition and 7 per cent for those with diabetes.

The third column shows the chronic health conditions in the patients who died.

More than a third of them had high blood pressure and 20 per cent had diabetes or heart disease.

Dr Rojas Alvarez said most of the people with respiratory diseases who died would have had chronic obstructive pulmonary disease (COPD). COPD is a group of lung diseases that includes emphysema and chronic bronchitis.

She said the data on risk for people with asthma was limited because the prevalence of asthma might not be the same in China as other parts of the world, but would become clearer as the pandemic progressed.

"My guess is anyone with some kind of pulmonary condition, like cystic fibrosis, or people who are smokers or former smokers, they might be at higher risk," she said.

Millions of Australians are potentially at higher risk

The chart below shows just how many Australians might be at risk of severe disease or even death because of existing illnesses.

While many are aged 65 and over, there are still millions of younger Australians who have health conditions that increase their risk of severe consequences.

Dr Rojas Alvarez said it was possible many of the people with chronic diseases who died were also in the oldest age groups.

She said countries like China and Italy, where the pandemic first struck, were not able to isolate their elderly populations as quickly as countries like Australia, the US and those in Latin America were now doing.

"So now we might start seeing those other severe cases and understand better the severity of infections in the other populations," she said.

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