My personal theory is: If they can't even run census without it being hacked - how can they guarantee your info isn't safe from those outside the medical profession?
I opted out months ago.
There is regular illegal accessing of police records (licence details, convictions, accident reports) when bribes are offered to staff members on behalf of employers or insurance companies .......
The same could happen with the medical records. It could be the reason for insurance claims being knocked back, or the reason you don't get that job that you are perfectly suited for.