How do you know that there won't be another shock? Bad things...

How do you know that there won't be another shock?
Bad things come in threes you know.
Bushfires, Pathogen.....what's next?
An invasion while our guard is down.
Boats from the north!!!!!
Hijacked ocean liners full of sick people.

.......and they might not actually develop a vaccine that works.

So cut off Australia indefinitely??