Pre-Exposure Prophylaxis or PrEP

Pre-exposure prophylaxis (PrEP) involves putting HIV negative people on antiretroviral drugs (ARV) with the aim of protecting them from HIV infection. This blog looks at some of the pros and cons of PrEP.

Wednesday, February 2, 2011

If You Need PrEP, You Probably Won't Receive It

Although not yet approved for use as a pre-exposure prophylaxis for men who have sex with men, CDC has issued guidelines for its use, a sort of de facto approval. But the guidelines make it clear that this is an expensive drug, intended for recreational use among those who can afford it. It's certainly not for people who live in the handful of African countries where HIV prevalence rates are the highest in the world.

For example, confirming that someone is at "substantial, ongoing, high risk for acquiring HIV infection" is going to be a bit of a challenge for the UNAIDS dominated prevention strategies in developing countries. As far as they are concerned, if someone is African and has sex, they are at high risk. The majority of infections occur among those engaging in what is essentially low risk sex. The contradiction doesn't bother UNAIDS.

Regular testing for those on PrEP is out of the question for most people in countries where most people are never tested and HIV positive people usually find out their status by the time their problem is AIDS rather than HIV. Similar remarks apply to regular sexually transmitted infection testing; poor countries don't have the health infrastructure to do this sort of work on large sectors of the population, even if they could identify which sectors those happen to be.

And so on. The measures recommended by CDC are pie in the sky for developing countries, where HIV prevalence wouldn't be nearly as high if they had such strong health services. And as for the remarks about adherence, the trial results cited completely fudge this issue. The overall 44% lower likelihood of acquiring HIV is constantly qualified by the higher figure achieved by those with high levels of adherence.

How about the lower figure for those who achieved the lowest level of adherence? People who fail to adhere to drug regimes or other measures that are intended to reduce risk of contracting HIV and other diseases are the very people who are at the highest risk. In other words, those least likely to adhere, and therefore to benefit from Truvada PrEP, are the ones who should be targeted. That's according to the guidelines, anyhow.

African populations are handy for testing out HIV drugs because there are very high levels of HIV transmission in many areas. But this drug is not intended for them. It is intended for those who wish to continue having risky sex but to minimize the risk of contracting HIV. The less risk they take, the better Truvada will work, but the less they will need it. The more risk they take, the worse Truvada will work and the more they will need it.


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