Is it for people that are exposing themselves to potential carriers in unsafe ways? Is it a way to slowly kill of the disease in populations (if everyone that would be exposed would be taking it)?
I'm genuinely asking as I haven't come across it before and I wonder if it's just because i'm sheltered or other reasons (I live in the UK so maybe that?).
It's this largely. The most obvious group in the UK are MSM men. It has to be taken more or less all the time by people who expect they may have encounters in which they could potentially be exposed, similar to the birth control pill.
People have been doing that even before PrEP. I hate to even mention these people, but they do exist and people should know.
https://en.m.wikipedia.org/wiki/Bugchasing
They're a tiny minority in the gay community.
> Is it a way to slowly kill of the disease in populations (if everyone that would be exposed would be taking it)?
The drugs are very expensive, and are not side effect free. Still much better than HIV. That is why MSM (men who sleep with men) and serodiscordant/serodifferent couples (where one partner is positive and the other is negative) are the groups targeted with these drugs.
Here’s some other scenarios that I think are more common:
1. Couple (who may be serodiscordant) wants to have unprotected sex.
2. Group of close friends want to have unprotected sex (think of it like a coronavirus social bubble).
3. People in (1) or (2) might have an arrangement that allows protected sex with others, but what if the condom breaks? Or someone lies?
4. People may be involved in risky behavior without making a principled risk assessment at all, possibly under the influence of drugs or otherwise without consent.
Being on PrEP helps mitigate risk in any of these circumstances. Also, most PrEP programs require STI testing every 3 months (for a variety of conditions in addition to HIV), along with surveys and some level of counseling on safe sex practices which measure whether the program is working. I suspect the bundled mandatory STI testing may actually provide more public health benefit than the PrEP itself.
A lot of people think of PrEP as being like the birth control pill. It doesn’t address all of the downsides of sex, but it mitigates the main risk, and can be used in combination with other methods to reduce residual risk.