[blue_dragon]

My "pragmatic" analysis:

I once spoke to a primary-care doctor about the risks of getting HIV through sex. The doctor told me that the risk of getting HIV the "typical way" (receiving anal sex) is about 1/72. Thus, for every 72 exposures, the recipient would contract HIV one time. This assumes that condoms are not used, and that the transmitter has an untreated HIV infection, which presumably has a high viral load.

Transmission risk goes down by orders of magnitude for other forms of sex, until we get to receiving blowjobs, where the risk is literally nil. There are zero recorded cases of HIV caused by receiving a blowjob.

In other words, HIV is actually kind of hard to get. You have to be very active, and not using protection, in order to get it. Or just be very, very unlucky. And that's with respect to untreated cases, which likely have high viral loads.

This suggests to me that, for practical purposes, undetectable levels are impossible to transmit. Or as the Prep marketing executives would say, "U means U" - undetectable means untransmittable.

Whether or not you're comfortable having sex with someone who is HIV+ but claims to have an undetectable viral load is a separate question entirely.

[jsperx]

I was ready to quibble with whether a primary care doctor would have the most reliable statistics on this topic but I found this source, with linked study, that implies (s)he is dead on: https://www.aidsmap.com/about-hiv/estimated-hiv-risk-exposur...

(Also estimates chances for other risk profiles, including 0% for undetectable.)

Seems like you’ve got a good doc there

[spencerchubb]

> Whether or not you're comfortable having sex with someone who is HIV+ but claims to have an undetectable viral load is a separate question entirely.

If someone has HIV, they would have to be extremely suicidal to forego taking the medication that would make them undetectable.

[tidenly]

Sorry to rant a little, but as someone who grew up with HIV in the family, this odd pressure against people who might be hesitant to sleep with someone U=U always feels uncomfortable and manipulative to me. I see it a lot around the internet.

The way I was raised, I'm the only person I trust with my sexual health. I would never trust someones word they're tested recently and have unprotected sex with them. I wouldn't trust someone saying they're on PrEP and have unprotected sex with them either. I can only trust myself. U=U is exactly the same situation.

In a zero trust mindset like that, someone telling me they're U=U only tells me they have HIV. I have HIV+ friends who struggle to take their meds at the right time every day, or forget. And I also know people who have lied about when they last took their STI screening to hookups.

I'm also sure a bunch of people would get angry if you asked a U=U person to show you their latest CD4 count or viral load proof too - so what am I to do, just trust that, unlike everyone else, U=U people are perfectly honest, and never screw up taking their meds?

The response to this is often "anyone COULD have HIV, U=U people are actually safer because they have it locked down", but again to me this is about as trustworthy as "anyone COULD have HIV, but people on PrEP have it locked down". It all relies on the trust the other person is on top of their shit.

[perlgeek]

Unfortunately, consistent self-care isn't easy for many people struggling with mental health issues.

Since you don't immediately feel worse after not taking your pill once, it's very easy to slip up if you aren't the most organized / functioning person.

[nerdjon]

It’s interesting. I never really thought to ask about the chances with anal given that going on prep wasn’t really even a question.

I knew it wasn’t one exposure and you would get it, but I honestly kinda figured the chances were higher than that.

Regarding oral, I was under the impression that the important caveat there was assuming you had no major sores in your mouth (like, maybe don’t do it after getting dental surgery). Since the reason it’s nil is due to the acids in your saliva and stomach, at least that is what my doctor told me.