Safer sex in a pill

Safer sex in a pill - health - 19 November 2008 - New Scientist

As a gay man living in the US, John has seen every kind of AIDS awareness campaign out there. He is intelligent and well informed, yet sometimes he has unsafe sex. He never plans to, but he does not always have a condom handy and occasionally, on the spur of the moment, decides not to use one.

Such behaviour is not that unusual among gay men, but unlike most, John (not his real name) isn't leaving himself totally exposed. That is because his doctor is willing to do something most would not countenance - prescribe John a medicine that could lower his risk of catching HIV.

This strategy is called pre-exposure prophylaxis, or PrEP, and John gets it from Marcus Conant, a doctor with a long history of standing up for gay rights. PrEP has yet to be proven in clinical trials, and Conant will only prescribe it for a select group of his patients - those who understand the limitations of this tactic. But if the most optimistic predictions are borne out, by taking a pill once a day John is radically reducing his risk of infection even if he has condom-free sex with as many people as he likes. It is more likely that the medicine has a modest effect - perhaps reducing the risk by around two-thirds - but even so, it significantly improves John's odds in the dicey game he plays...