From a Nine News report (March 16, 2020):
...it comes as our medical authorities predict that in the best case scenario 20% of the Australian population will be infected, that equates to around 5 million people...
There's a similar claim in The Australian (March 13, 2020):
Most experts are optimistic that Australia will be able to keep transmissions of COVID-19 to the low end of projections. But even the best-case scenario is grim: NSW’s Chief Health Officer predicted this week that 1.5 million people, or 20 per cent of the state’s population, will be infected. At a death rate of 1 per cent, that would mean 15,000 dead in NSW alone.
For a "best case scenario", it seems extreme, far worse than China. I'd like to see how they came to that conclusion.
Question: Is it realistic that "in the best case scenario 20% of the Australian population will be infected" by the novel coronavirus?