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.

Tuesday, November 9, 2010

Millions of Pills Haven't Worked So Let's Try Billions of Pills

The 'treatment as prevention' approach to reducing HIV transmission is getting airtime again, this time because the pioneer of the strategy has receive the Einstein award. Treatment as prevention is more of a hypothesis than a strategy or approach, really. But given the rarity of feasible HIV prevention strategies the HIV industry needs something to obsess about.

The hypothesis suggests that, because successful HIV treatment reduces the viral load to the extent that HIV positive people are very unlikely to transmit the virus, prevention programs could rely on this to significantly cut HIV transmission.

The number one flaw in the hypothesis is that it assumes that most HIV is transmitted sexually. This is a rash assumption in countries where health service provision is of extremely low quality. But the HIV industry has little interest in health or health service provision when they can sell lots of drugs. And it's a media friendly issue, with its combination of technical fix and the implication of illicit sex.

Of course, rolling out treatment to as many HIV positive people as possible when they need them is a good thing. But it may not have much impact on transmission rates. And ensuring that they didn't become infected in the first place would be preferable. It is hardly reassuring to those who are currently HIV negative that so little is going to be done to help them stay that way.

Another flaw is the assumption that a disease can be eradicated by some technical fix when the circumstances under which the disease became an epidemic are left pretty much as they are. So there is no need to improve health, education, infrastructure or social services? But these questions are not popular in the industry.

HIV testing has been around for some time now, in developed and developing countries. Most people never get tested, others test once and never again. But treatment as prevention requires the majority of people, or as near to 80% of people as possible, to be tested regularly, perhaps once a year.

It remains to be seen how many developing countries will be able to encourage such huge numbers of people to turn up for testing every year, or even how such programs will be administrated in countries where health services are so poor. High prevalence countries currently have a lot of trouble accounting for the HIV positive people they know about, a fraction of the total infected.

The above article on the award raises the issue of 'risk compensation', where it was feared that the availability of HIV treatment that also reduced infectiousness might result in increased risky sexual behavior. But where sexual behavior is not the main driver of HIV transmission, this is something of a red herring.

It's great to hear that treatment as prevention works so well in British Columbia. But I don't think the health problems in BC are anything like the health problems in East Africa. And I'm pretty sure the health systems (also education, social services, infrastructure) in BC are not like those in East Africa.

In short, the technology on its own is not the solution to an epidemic that has many determinants. This technical fix may have some impact in isolated pockets of East Africa, especially in randomized controlled trials, but people need a lot more than just pills to stay healthy. Far from obviating the need for decent health services now that some great technology is available, that technology requires adequate health services, and probably education, infrastructure and social services.


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