It is undoubtedly true that people who have sex only with opposite-sex partners can acquire HIV. See eastern and southern Africa for a totally dystopian example.

But it is equally true that targeting at-risk populations is critically important in combating the virus.

In the United States and Europe, at least, that means targeting men and transgender women who have sex with men. It’s not as useful to talk about gay and straight. Many men who have sex with men do not identify as gay or bisexual.

Nonetheless, the virus remains stubbornly in circulation primarily in pockets of those populations, which is why the US government is targeting those populations with education and treatment.

Stigma is one of the reasons that the education and treatment drives are so important. HIV stigma often acts as a barrier to testing among people who are at risk, and a barrier to effective treatment strategies for people who control health budget purse strings.

Public health experts in the United States say that if more young men who have sex with men had access to regular testing, and either pre- or post-infection treatment, then HIV would likely stop circulating.

That’s why education and testing and treatment campaigns focus on men who have sex with men, and particularly on men with lower socioeconomic status. Wealthier gay men, after all, mostly already know about prep or treatment as prevention.

HIV prevention campaigns here do not focus on people who have sex with partners of the opposite sex, because HIV is mostly not circulating in those populations. Public health authorities don’t think putting all young people on prep would be either efficient or practical.