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.

Thursday, November 24, 2011

Treatment is Not Prevention, but it is Far More Lucrative

It's a relief to hear that there are some people working with HIV who are willing to speak out against the apparent assumption that treatment is prevention, that all we need to do is substantially increase the number of people taking expensive antiretroviral therapy (ART) for the rest of their lives, regardless of the known consequences of such a strategy, and HIV transmission will magically decline and eventually disappear.

Alison Rodger, Andrew Phillips and Jens Lundgren recommend that before adopting ART as a prevention policy, we need to assess the risk of HIV transmission through unprotected sex (ie, without a condom) when the viral load is undetectable. So far, research has revealed that transmission could be unacceptably high under such circumstances, but neither the media nor the academic hype around treatment as prevention has alluded to this.

Xiaohua Tao, Dan Shao and Wei Xue call for an assessment of how a policy of treating HIV positive people at an earlier stage of disease progression would affect their sexual behavior. They point to evidence that use of ART increases risky sexual behavior. They also express worries about the development of resistance to ART, which is one of the known consequences alluded to above.

Enthusiasts of the treatment as prevention strategy, Myron S. Cohen, Ying Q. Chen and Thomas R. Fleming, accept that the benefits of ART are unknown where condoms are not used as part of the strategy. They also note the frequent occurrence of pregnancy and sexually transmitted infections (STI) among trial participants, which suggests that self-reported sexual behavior was not so accurate, or that condoms are a lot less effective in reducing STI transmission and pregnancy than we are led to believe.

Essentially, Cohen and colleagues are a bit vague with one of the real worries about a treatment as prevention strategy: the lack of clarity about how HIV is transmitted so rapidly in only some countries. The orthodox view is that heterosexual sex is responsible for 80-90% of transmission. But why should a virus that is difficult to transmit through penile-vaginal sex be transmitted so rapidly in certain populations? Do they all secretly engage in anal sex? Or are there non-sexual risks that some of them face?

Uganda is an interesting case in point. The orthodoxy gather up lists of 'most at risk' people, men who have sex with men, intravenous drug users and the like. They also add in sex workers, truckers and other groups who are said to be vulnerable because of their 'mobility', whatever that may mean. But there is always the assumption that heterosexual sex is the key. Yet none of these circumstances explain massive rates of transmission in some countries, where most people don't fall into any of those groups said to face high risks.

Indeed, the majority of transmissions in Uganda and other countries are among people who do not face high risks, they fall into low risk categories, even by the strictures of UNAIDS and others in the industry. Don't these astute people notice the contradiction in their claims, that most HIV transmission occurs among low risk people, those who do not have high risk lifestyles? What is it about Ugandans? Is it their sex lives, their sex organs, or something else?

It's not just treatment as prevention or any other smug strategy that will fail if we don't make it clear how HIV is being transmitted, why it is being transmitted amongst people whose ostensible risk behavior levels are low and why doling out ever increasing amounts of drugs to ever increasing numbers of people should make any difference; because, so far, for every person put on drugs, two become newly infected. If putting 6 or 7 million people on ART doesn't reduce transmission, why should doing so with 16 or 17 million, or more?

Treatment is not prevention and until the actual modes of transmission, rather than assumed modes of transmission, have been properly assessed, HIV prevention efforts in Uganda and elsewhere will continue to be as unsuccessful as they have been so far. The fact that ART keeps HIV positive people alive does not mean that it will keep HIV negative people negative. It may help, but it is not enough.

[For more about non-sexual transmission of HIV through unsafe healthcare and cosmetic services, see the Don't Get Stuck With HIV site and blog.]


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