The entire border. Coast-to-coast. Nobody but Australians in and out. And if they are returning then they must go into three weeks quarantine with jail if violated.
Why? Because there is no point doing half measures with COVID-19. If the virus gets in then it is going to wreak havoc. The entire private sector, and much of the public, will shutter the moment it reaches critical mass.
It is not far away and has already begun. Yesterday I went to the local shops for a coffee and there was nobody there. I asked the barista how it was going and he replied it had been very slow all week. Then I got an Uber to the mall. Same response. In the mall, same response.
Remember too that come June, when the virus is passing in the northern hemisphere, it will be ramping to an August super peak locally. Everyone else will have travel bans on us anyway.
Now, consider the counterfactual. If we shut the border ourselves right now and stamp out the virus while we still can (and we can given it is still early Autumn). Within weeks Australians will be reassured that out great moat has protected us from the infection.
They will begin again to go about their business. Many will live who might otherwise die. The economy will take the external shock but not the domestic one and be FAR BETTER OFF over the journey.
Shut the border right now, Canberra. Not another of the pretend border protections that you’re so good at. A full blown quarantine Downunder.
Your half-arsed measures have us on the path to the worst case scenario: the most dead and the most economic harm.