That is largely a luck and legacy thing. inReach is an acquisition by Garmin. They haven’t made significant changes to hardware and software besides rebranding things and adding integration to their newer units, e.g. I can trigger SOS from my watch.
As a gay man on prep, I find this comment quite offensive.
Within my circle of friends (some of whom are quite adventurous) none of them says “let’s donate blood and see what happens”.
Furthermore being on PrEP requires strict complete STD testing (Chlamydia, Syphillis, HIV, included) testing every 3 months before allowed to be prescribed again. The same time interval as any recommended STD testing.
I had a discussion with my Dr last week about Truvada on similar topic. Her reply was that Truvada is not enough to suppress viral load and thus they can be detected if a person is infected still and is not on treatment. Also Truvada is not magic pill and can take time to take effect (about 1-2 weeks) and there have been cases of people getting infected while on PrEP because their drugs haven’t taken effect yet.
In fact the billing is completely separate.