I guess the question is, is the PrEP-protected infection rate among people having unprotected sex while on PrEP, lower or higher than the not-protected infection rate among those who would have unprotected sex even without PrEP?
PrEP is for hiv negative people.
If you’re virus level is undetectable from treatment, then you’re not contagious.
It's a rather academic distinction given that it's the same drugs in either case. Definitionally, it's PrEP only if those drugs are being taken as a preventative measure.