It sounds like science fiction, but there’s no question it works. Late last year, I wrote about the ‘debate’ over PrEP, short for pre-exposure prophylaxis, which allows people who are HIV-negative to take a daily pill to prevent getting infected. It works whether or not condoms are used, and therein lies the rub: people who are opposed to gay men and transgender people getting it on freely tend to oppose PrEP as well. This, along with the fight for same-sex marriage, has reheated an older debate about gay ‘promiscuity’.