my (possibily) limited understanding is that Australian health providers use international health codes as a matter of course (for example, when a hospital uses the medicare item number to claim payment for a service provided)
gross data is compiled more or less at the same time (if that is technical enough for you)
I would be astonished if any personal identifying data makes its way into the national figures we share.
If the performance of government software e.g. sennalink's my gov is any indication, nobody is getting their hands on much