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.

Friday, May 20, 2011

HPTN 052: A Drug is not, and Never Will Be, Health

The HPTN 052 trial, which found that treating HIV positive people with antiretrovirals reduces transmission to their sexual partner by '96%', has been reported far and wide. That's great, up to a point. It means that HIV positive people can benefit from early treatment, another finding of the trial. But more importantly, it means that HIV positive people's HIV negative partner can enjoy a very high degree for protection.

What the reporting does not point out is that, while HIV positive people's partners are protected, not everyone is infected by their partner. The HIV positive people in discordant couples, themselves, were probably not infected by their partner. The might have been, but it's more likely that they were in a position where they would not have been protected by the sort of program suggested by the results of the HPTN 052 trial.

In fact, a very high percentage of new HIV transmissions in countries such as Uganda are estimated to occur in long term, monogamous couples, perhaps over 40%. But only some of these new infections occur within the couple. How do people think discordancy occurs in the first place?

What this means is that, once someone is infected, their partner (or even future partners) can be protected. So treating everyone in a discordant relationship will protect partners not already infected. But HIV prevention needs to go beyond targeting those who are already infected if they are to protect those who are not yet infected.

The theory is that everyone (or about 80%, even) in a population is to be tested for HIV regularly and anyone found to be HIV positive can be put on treatment straight away, instead of waiting, as is done currently. It is even claimed that it is possible to test everyone every year, and this may be true. But no one has demonstrated that yet, certainly not the HPTN trials.

So far, the majority of people in high HIV prevalence countries have never been tested for HIV and the majority of those who have tested have only done so once. Testing programs might one day be scaled up and testing may become something people do every year, like paying their taxes. Or it may not. And the so called 'test and treat', 'treatment as prevention', 'treatment is prevention', whatever it is called strategy requires regular testing for everyone, or at least a sizeable majority.

All the necessary elements may one day be achieved, but it is premature, and irresponsible to claim that "we now have the tools that could end the HIV pandemic" or that "HIV is 100 percent preventable", or, indeed, that "treatment is prevention". Treatment is, and has been for some time, part of prevention. But we can't eradicate HIV simply by throwing unlimited quantities of drugs at the disease.

[There's more about Treatment as Prevention on my other blog, HIV in Kenya.]