Coronavirus: Early modelling estimates the risk of severe illness for different age groups

Early modelling has revealed the differences between age groups when it comes to being hospitalised with the coronavirus and the chances of getting seriously ill.

Early modelling released by the Morrison Government has provided insight into how likely certain age groups are to get seriously ill from COVID-19.

The paper from The Doherty Institute includes estimates for each age group of how likely they are to need intensive care treatment.

Prime Minister Scott Morrison has stressed the modelling is theoretical and was based on overseas data, not what was actually going on in Australia.

The paper itself noted that the modelling was limited by ongoing uncertainty around the true disease “pyramid” for COVID-19, and the lack of information about why some people get a more severe form of the disease. It has also not been peer reviewed.

The modelling developed “assumptions” about hospitalisation rates for different age groups to simulate the virus’s impact on the Australian health care system, and to inform the Morrison Government’s response to the pandemic.

Based on overseas data, it estimated that those aged younger than 19, had a less than 1 per cent chance of being hospitalised or requiring intensive care treatment.

Those aged between 20 and 29, also had less than 1 per cent of being hospitalised but this rose to almost 3 per cent for those aged between 30 and 39.

This compares to those aged 80 and over, who had a 65 per cent chance of being hospitalised and up to 19 per cent chance of requiring intensive care.

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During a press conference on Tuesday, Mr Morrison and Chief Medical Officer, Professor Brendan Murphy, continued to defend the government’s decision to keep schools open.

Prof Murphy said symptomatic disease in young people was still extraordinarily low.

“We have not found any evidence internationally of significant school-related outbreaks,” he said.

He said he could see no reason why children shouldn’t go to school.

“The AHPPC (Australian Health Protection Principal Committee) advice is that there is no reason to withhold children from school,” he said.

“We do think schools need to be made safe, and the National Cabinet has asked us to come back later this week with some detailed advice on how to make schools safe, in terms of hygiene measures, reducing gatherings, practising where possible social distancing, cleaning playground equipment, all of those things.

“But we believe that there is not an evidence base to say that keeping children from home is a strong public health measure on the current evidence that we have.”

The Prime Minister said National Cabinet and individual premiers had made changes to schools based on the workplace health and safety issues for staff, including the teachers, at the school.

“It has not been done on the basis of the health advice, at least from the AHPPC, regarding any health risk to the children,” he said.

It’s hoped that more accurate modelling based on data from Australia will be available in the next few weeks.

The paper also highlighted the potential strain that could have been put on Intensive Care Unit beds in Australia if strict social distancing measures had not been introduced.

If the government chose only to isolate sick people and quarantine others likely to be infected, without introducing social distancing measures, an estimated 67.5 per cent of Australians would have been infected with COVID-19.

In addition, only 30 per cent of those who needed ICU care would have been able to access this.

Mr Morrison said while the modelling was theoretical, it proved the theory of “flattening the curve” and that measures Australia had taken could make a difference.

“Indeed, that is what we’re experiencing here in Australia,” he said. “We are on the right track.”