Yes, we're flattening the coronavirus curve but modelling needs to inform how we start easing restrictions
- Written by Tony Blakely, Professor of Epidemiology, University of Melbourne
Australia is on track to flatten the curve of coronavirus cases, which will allow our health system to cope with increasing demand for intensive care unit (ICU) beds, recently released modelling confirms.
The modelling, produced by the Doherty Institute, was delivered to government in February but only released publicly yesterday.
In a press conference before the release, Prime Minister Scott Morrison and Chief Medical Officer Brendan Murphy emphasised the modelling was theoretical and used international data.
International data is still useful – the public health advice on tobacco, for example, is derived mostly from non-Australian studies.
But the way an epidemic plays out is context-specific. The way Australians hang out together, for instance, is different from the way Chinese people socialise. This changes fundamental parameters, such as how many people someone with COVID-19 can be expected to infect.
So what does the modelling tell us and what are we yet to determine?
What scenarios were modelled?
The more applicable of the two papers released yesterday aimed to estimate how much ICU and hospital capacity would be exceeded (in both percentage terms, and number of days) for various scenarios of how the epidemic unfolds.
The three scenarios were:
unmitigated spread (just “let the epidemic rip”). Peak daily ICU demand would be 35,000 a day, greatly exceeding Australia’s expanded ICU capacity of 7,000 beds
quarantine and isolation of cases scenario. The number of ICU beds needed during the peak would be 17,000 a day, still exceeding Australia’s expanded capacity
a quarantine and isolation scenario, plus social distancing at two levels of intensity. Daily ICU bed demand would peak at below 5,000.
Australia was never going to allow unmitigated spread and has implemented quarantine and isolation of cases. And in terms of social distancing, Australia has already exceeded the measures in the paper’s more intense scenario.
Lukas Coch/AAPWhat do we learn from the modelling?
As we’ve learnt over the past month from simpler models and back-of-the-envelope calculations, ICU capacity is under grave threat of overload for anything other than a carefully designed, tested and monitored package of case isolation, quarantine and physical distancing.
Physical distancing is essential to flatten the curve enough to avoid ICU overload if we elect to let this epidemic wash through society to achieve herd immunity.
Read more: Coronavirus: can herd immunity really protect us?
Authors: Tony Blakely, Professor of Epidemiology, University of Melbourne