ANALYSIS

Coronavirus modelling has been released giving strict measures some context

The modelling has finally been released, we will be able to avoid a worst case scenario?
The modelling has finally been released, we will be able to avoid a worst case scenario?

The coronavirus pandemic has arrived fast in slow motion. We watched as Wuhan was engulfed in a horror we could feel but which Australians without a connection to China could comfortably regard as foreign.

When Australian children started school at the beginning of February, cases stood at 12. By March 1, just 27 people had been confirmed with the virus. Italy was touching 1700.

That was barely a month ago. Now, Australia has 5800 cases and Italy 132,500. The pandemic has overwhelmed hospitals and frightened medical workers in New York. In Britain, Boris Johnson is in intensive care. Australians without a Chinese connection, will have one in Italy, in the United States or in Britain. The horror has become real for many, and now we finally have the modelling that shows what the virus might have been capable of here.

It has not, frankly, been presented in the most straightforward way, and it does not, oddly, mention the word death, other than to say how many have died to date. That is clearly a level of detail with which the authorities are not yet ready to trust us.

The Prime Minister and chief medical officer were also at pains on Tuesday to point out that the worst-case scenario was firmly in the zone of theory and, they said, completely unrealistic.

It does, however, explain why the pub is closed and you're sitting at a cobbled-together desk being over-sold as a home office with the kids at your feet and grandma in isolation.

As Doherty Professor of Mathematical Biology James McCaw said on Tuesday, his team had "put some scary numbers to the government early on", and, happily, "that wasn't dismissed". Instead, the government listened, which has "served us and our community well".

However, "what is absolutely clear is if we relaxed all of the current measures that would turn into an explosive outbreak and we would be in a very poor situation very quickly," he said.

Those scary numbers include the fact that 65 per cent of over 80 year olds are expected to end up in hospital if they catch the virus, along with 36 per cent of people in their 70s.

Ten per cent of people in their 50s are expected to need hospital care and it gets better down from there. Five per cent of people in their 40s, 3 per cent of people in their 30s, and fewer than 1 per cent of people in their 20s or younger are expected to end up in hospital.

The scary numbers also suggested a pandemic left to run its course would see 35,000 people needing intensive care treatment on the worst day. Australia has 2200 intensive care beds and is ramping that up to 5000 using ventilators from other parts of hospitals. The government has also ordered another 1000 and is working up to about 7500, including non-invasive ventilators that help people breathe rather than breathe for them. None of that goes near 35,000.

The Doherty Institute modelling is aimed at finding a scenario that we can all live with, literally. Kind of.

The modellers looked at what happens to the numbers if you isolate infected people and quarantine contacts. Not enough. You still end up with fewer than one-third of the people who need intensive care beds being able to access them.

So they went further, adding in social distancing. Only then did they get close.

All of this assumes intensive care capacity can be tripled, making five times as many beds available for coronavirus patients (assuming there are 1100 intensive care beds available for coronavirus patients at the moment, 22 of them in Canberra).

The base case assumes an infection rate of 2.53 if the spread is unmitigated (with each infected person infecting 2.53 others).

When social distancing cuts the infection rate (the R0) to 1.9, there's still a shortage of intensive care beds, with 80 per cent of people needing them able to access them. It is only finally at the infection rate of 1.69 that intensive care copes with the numbers.

So there it is finally, the number that is keeping the national pandemic team and our political leaders up at night and driving what you see around you.

This story The magic number that will allow intensive care units to cope first appeared on The Canberra Times.