HIV is a terrible disease that affects over 33 million people worldwide. In developed countries it occurs primarily in gay and bisexual couples, whereas in the third world, HIV is seen foremost among heterosexual couples. There have been huge advances in HIV treatment and, at least in America, the disease often is chronic with patients living decades beyond the initial diagnosis. Still, an ounce of prevention is worth a pound of cure. To date other than sexual abstinence (which  is not a realistic option for most people) and regular use of condoms, nothing seems to prevent this disease. There is no HIV vaccine yet.

Along comes Truvada, a combination of two anti HIV drugs. This medication, which is very powerful, knocks out the virus before it can establish itself in the body. Among studied gay and bisexual men who took the medication, it reduced the risk of acquiring HIV up to 42% and even better, among heterosexual couples, up to 75%.

Just imagine, if popping a pill can reduce HIV risk by that much, why not give it to all sexually active adults? Well, for one thing, it costs a small fortune: At $13,000 a year, you can buy quite a few condoms. Those who need the medication the most are arguably those who cannot afford it. Truvada users might think-hey, it’s party time, and forget all notions of safe sex. Yet the pill is not 100% effective and reckless behavior will therefore still result in many more HIV infections. If the pill is only taken sporadically-say before a hot date, then resistant HIV viral strains will occur. HIV resistance is already a huge problem.

The bottom line is that for now Truvada might be better suited to the developing world, where most new infections occur among heterosexual couples. For Americans at high risk of HIV including gay and bisexual men, their partners, individuals with more than one sexual partner and intravenous drug abusers, Truvuda should be seen as another option for reducing, but not eliminating HIV risk.