One of arguments for encouraging high vaccine uptake although it’s not 100% effective (no vaccine is though) is that because it will still reduce spread massively, it will also reduce the chances of the virus mutating (as the mutations occur with each viral replication).
I don’t see why Victoria can’t eliminate delta. They expected the numbers to bounce around a bit as cases from the initial MCG exposures etc presented themselves. But it’s certainly not growing exponentially and the wastewater testing is a good indicator of what’s happening. (There’s currently a renewed alert and call for testing for Phillip Island as the known Covid cases are no longer there and fragments have started to appear in wastewater – so they know they should be looking for undiagnosed cases. Technology for the win 🙂)