Hah, whilst technically a quasi medical professional in real life, in this I am an ignorant layperson, but I thought immunity was exactly that, you didn’t show effects of an illness. So carriers, not sufferers. For example if you have already had a disease (say chickenpox) you can catch it again, but your immune response immediately kills it, which we call immunity. This is what the vaccine is designed to create.
I probably got the term wrong, but the principle is if 5% of people show signs prior to vaccination, only 0.5% will show signs post vaccination! So once the Australian population is vaccinated we can reopen, the state of the country of origin should be irrelevant!
The counter argument to this, is people arriving unvaccinated may put undue strain on our health system if they get sick...