Wednesday, September 8, 2010

Pre-Exposure Prophylaxis, Till Death Do Us Part

Pre-exposure prophylaxis (PrEP) involves putting HIV negative people on antiretroviral drugs (ARV) with the aim of protecting them from HIV infection. So far, such a use of ARV does not give 100% protection. However, like male circumcision and the use of topical microbicides, it could be used along with condoms. Or you could just use condoms.

But the ultimate aim is to develop PrEP that allows people to have safe sex without using condoms (otherwise they will tempt very few). Cynics even suggest that the aim is to allow men who have sex with men (MSM) in rich countries to have unprotected sex, but I don't quite buy that.

The fact that a lot of the clinical trials are taking place in developing countries doesn't mean the people there will eventually benefit from PrEP. But to the pharmaceutical companies that sell ARVs, developing countries represent a huge potential market. That's as long as donors can be persuaded to pay for the drugs. Costs are far beyond what people or governments in developing countries can afford.

There are many questions to be raised about how much the use of PrEP could really help reduce HIV transmission. But my question is about who, exactly, would be the targets of a PrEP program in developing countries, taking Uganda as an example (because I happen to have the Ugandan Modes of Transmission Survey handy).

You might think an obvious target for PrEP would be sex workers. But in the 2009 survey, Ugandan sex workers were estimated to contribute 0.91% of HIV incidence. If you add in their clients and the partners of their clients, that still only comes to an estimated 10.5%. PrEP rollout for these groups, assuming you could actually round them all up, would be very expensive. But it doesn't look like it would have much impact on the overall epidemic.

The largest single group, contributing 43% of total incidence, consists of mutually monogamous couples engaging in heterosexual sex. Bizarre as it may sound, most HIV in Uganda, a virus that is difficult to transmit sexually, is transmitted by very low risk sex.

Think of it this way, Kenya has several hundred thousand HIV positive people on ARVs, that's less than 1% of the population. Around 99% of that money comes from donors. And even that few hundred thousand people is beyond what the countries health services can manage, despite all the donor funding.

The sad truth is that, either you 'target' much of the sexually active population of Uganda, which is not really targeting, more scattergunning, or you will not have any sizable impact on the epidemic. But PrEP is simply not the sort of intervention that you can roll out to a large sector of your population.

An article about the costs involved in rolling out PrEP in Australia cites very high costs just for basic, first line drugs. At up to and beyond 10,000 dollars per person, for the rest of their life, this will not even be discussed in developing countries. And while the drugs will be available at far lower cost in places like Uganda, you are talking about millions of potential recipients. Resistance to first line drugs may only amount to 3 or 4% (if they are lucky) but you can multiply that five or ten times to calculate the addition to costs.

The drugs will be available at far lower prices because drug companies have an uncanny way of knowing just how much they can squeeze out of a 'marketing' situation. Rich countries will pay hefty sums for worthless drugs, or drugs worth very little but in huge quantities. Just look at Tamiflu and the stockpiles of it. They will pay less to purchase drugs for developing countries, but the quantities will be mind boggling and Western run institutions will agree to any price once it's in the hundreds of dollars, apparently.

Talking of Tamiflu, one of the main proposed PrEP drugs is Tenofovir, discussed in glowing terms and voluminous quantities during the Vienna Aids Conference. Another is called Truvada, a combination drug. Gilead is involved in all three.

Another name that crops up is Bill Gates and his Foundation, who are never far away if there is money to be made out of intellectual property. But what will the benefits of PrEP be? If Modes of Transmission Surveys like the one for Uganda are correct, almost everyone that has sex in high and medium HIV prevalence countries is at risk. They can't all be put on preventive drugs, even if it were possible to afford such an intervention.

It may sound as if I am claiming that an almost entirely useless HIV prevention strategy is being advocated for by the very pharmaceutical industry that stands to gain billions from it. And that's exactly what I am claiming. Big Pharma expect billions more dollars, on top of the billions they have already received, to flow from persuading donors to pay for up to tens of millions of healthy people to be put on drugs for a large part of their life, with little or no benefit and possibly a lot of damage. In a nutshell: pre-exposure prophylaxis or PrEP. Remember the name.

NB: I have set up a new blog to discuss the subject of pre-exposure prophylaxis or PrEP.


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