I have been thinking a lot about PrEP. It sounds so great when you first think of it. A simple, one-a-day pill to prevent HIV infection. Straightforward and easy. The obvious parallel is oral birth control pills. One pill every day and no pregnancy. Isn’t PrEp the same thing? Sort of? So why have I been thinking about it?
Pre-exposure prophylaxis (PrEP) involves getting anti-viral medication into your system before the HIV gets there so that if you are exposed to the virus the medication will prevent the virus from replicating and thus reduce the likelihood of infection from the exposure.
Several studies tried to demonstrate that this idea even works. Two large studies in women in Africa were stopped early because of futility. Of the nearly 7000 women studied, those on the prophylaxis agent didn’t have lower rates of infection than those not on the drug. But when they looked back at the actual drug levels in the women who were supposed to be taking the prophylaxis they found very low to negligible levels. The women weren’t taking the medication. That must have been so frustrating for the people running the study! But it did reinforce the lessons from oral birth control medications: if you miss more than two days, all bets are off.
Two other studies, one in heterosexual discordant couples (one spouse HIV + and one HIV -) and one in men who have sex with men (MSM), did show significant differences between the groups taking PrEP and those not taking PrEP. Adherence was better in these groups, evidenced by higher drug levels. These study subjects perhaps had more motivation, more direct confrontation with potential risk in their partners.
So it seems that the question -does it work?- has been answered. If you take PrEP you can reduce your risk of infection from HIV. That is, of course, important to know. But this leads to many new questions. I wonder who should take PrEP – should it be any sexually active person between the age of 15 and 24? That’s the group where we are seeing the most new infections these days. Should it be all sex workers? Should it be anyone in a serodiscordant relationship? Anyone who has anonymous sex? Anyone who has sex? Anyone who thinks they might have sex? Anyone who thinks? It’s not simple.
Another line of questions has to do with the drug used in all of these studies, tenofovir. It’s a drug that we use very commonly for HIV treatment and we rely on it. Does using it for prophylaxis take it away from someone somewhere who needs it for treatment? Does it risk creating virus that’s resistant to that drug? And this drug can cause kidney problems in some people. We watch for this in our HIV patients on medications. How closely should this be monitored in people who take the drug for PrEP?
Who is going to pay for PrEP? Will our healthcare system? Will insurance? Will the church? These days the answer might be “none of the above.”
Will taking PrEP give someone a sense of security that leads to more risky behavior such as more anonymous sex or skippping other, important forms of protection such as condoms?
There are lots of other questions raised by the concept of PrEP. Not all will have clear answers. I keep thinking about it.
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