Sorry if this has been covered, I've read many responses but not all.

Just on a practical note, would "medical grounds" include for example, if my child caught chicken pox before she could be vaxxed for it? (Which she did, because her big sister's CP vax didn't work and she caught it and infected the rest of us... ). Does the dr notify this through the standard process? I know they do when your child is vaxxed, and you get the immunisation statement in the mail, but now we're technically behind, so I just wondered what to do about closing the loophole. Not overly concerned about the entitlement (although I won't sneeze at it - goes towards a rare holiday in our family), but more about having it clearly stated that DD2 is not in need of the CP vax.
Yes, having CP makes you exempt from needing the vax. I'm pretty sure that would be covered as a medical exemption and you need your doctor to sign the form for you submit for an exemption from the CP vax to make you 'up to date' on the immunisation schedule.