Because Australia is an island (big one, but still) and thus, it's fairly easy to close the borders. You simply don't allow anyone to enter, close all airlines and voilà.If I'm not mistaken this person got the british strain while not having been outside of the country?
That must main other people have it too which is a bit worrying looking at the state of hospitals in london right now.
Let's hope it'll stay at 3 days and nothing more is needed.
So far australia seems to have handled it a lot better than europe did...
And what might help, it's summer time now. We had low figures in summer last year as well! But people are still going anywhere without thinking about what they're doing. "No, we have booked our holiday, we will go to our holiday. We paid for it goddamn!"