> In the US, 0.4% of adults have HIV [1]. With >20 sexual partners the cumulative exposure becomes meaningful. Naively, 20 repetitions of 0.4% gets 7.89% exposure risk.
Nope. The 0.4% is overwhelmingly concentrated in men who have sex with men. It's approximately an order of
magnitude lower in women.
Based on your envelope math, I should have a >90% chance of having HIV, but that's nowhere near the truth (and I don't).
> The 0.4% is overwhelmingly concentrated in men who have sex with men. It's approximately an order of magnitude lower in women.
I added a note to interpret with caution because many factors can significantly affect this figure. Some states have an order of magnitude difference from others, potentially offsetting the MSM factor you mention [1].
> Based on your envelope math, I should have a >90% chance of having HIV
The envelope math was exposure not contraction. If you used or condom, or even just received oral, it's quite possible you didn't get HIV even if your partner did.
> The 0.4% is overwhelmingly concentrated in men who have sex with men. It's approximately an order of magnitude lower in women.
True, but it's also true that male-to-female transmission is easier than female-to-male transmission, which makes the odds better for the man in any given encounter.
Nope. The 0.4% is overwhelmingly concentrated in men who have sex with men. It's approximately an order of magnitude lower in women.
Based on your envelope math, I should have a >90% chance of having HIV, but that's nowhere near the truth (and I don't).