Pre-Exposure Prophylaxis: A New Tool in the HIV Prevention Toolbox
Can a pill really be taken that will prevent HIV infection? Some new studies say “Yes.” The use of pre-exposure prophylaxis (PrEP) is not a new concept; for years malaria drugs have been given to travelers visiting areas where there is a high risk of contracting the disease. However, the use of PrEP has never before been looked at as a prevention method for contracting HIV.
So what exactly is PrEP and how does it work? Current studies are testing the effect of using a daily regimen of antiretroviral treatments to prevent infection with HIV. Two drugs are currently being tested for this purpose in clinical trials: tenofovir and Truvada (a combination of tenofovir and emtricitabine). In November 2010 the National Institute of Health released the results of the iPrEx clinical trials. These studies were conducted with men who have sex with men in six different countries. In the study, there was an overall 44% reduction in acquisition of the virus in men who took a daily oral regimen of Truvada. Additionally, blood samples showed that there was a 90% risk reduction in men who faithfully took the drug daily.
In two more recent studies, PrEP has been shown to be effective in reducing the spread of HIV between heterosexual partners as well. The Partners PrEP study compared tenofovir and Truvada regimens in heterosexual partners where one was HIV positive and the other was HIV negative, in Kenya and Uganda. In this study, tenofovir was 62% effective in preventing HIV infection while Truvada was 73% effective. In another study, TDF2, researchers looked at a Truvada regimen in heterosexual men and women in Botswana. This study found Truvada to be 63% effective in preventing HIV infection. Although the adherence in both studies was somewhat high, 97% and 84% respectively, the researchers noticed that the adherence was higher in couples, especially when they received adherence and sexual health counseling together. Therefore the drug appears to be more effective when it was taken along with practicing other safe sex methods.
What do these new findings mean for combating the AIDS pandemic? Firstly, they give medical practitioners another tool to fight the disease. Previously, condoms and abstinence were the only ways to prevent the spread of HIV. However, more recent discoveries have given us other ways to help curb the spread of the disease: vaginal microbicides, immediate ART treatment to prevent HIV transmission and now PrEP. Combing these new prevention methods with the traditional prevention strategy of condom use could be an extremely effective way to reverse the trends of the current pandemic.
Second PrEP allows individuals, especially women, to have more control over what happens to their bodies. Many women may not be a position to negotiate condom use, for example if they are in abusive relationships or live in societies where women have no self autonomy, and PrEP would give them another way to protect themselves against HIV. Unlike a female condom which is visible to the eye, a woman could potentially be on a PrEP regimen without their partner ever knowing.
Despite the potential benefits of PrEP, there are still a few major concerns. One problem with such a breakthrough is that it may discourage the use of other safe sex practices. If someone knows they can greatly decrease their chance of getting HIV by taking a pill they may forgo the use of condoms altogether. Not only does unprotected sex increase the chance of pregnancy, it also opens one up to a whole host of other sexually transmitted infections (STIs). STIs increase the chance of acquiring HIV, as well as lead to infertility and reproductive cancers. The most effective use of PrEP would be in conjunction with condom use and continual HIV testing.
Another issue with PrEP is cost and access to the medication. Condoms are cheap, drugs are not. Condoms can be handed out on the streets while drugs would require a doctor’s visit and a prescription. In areas where funds are already scarce, such as in Africa, who would have access to this prophylactic treatment? Would it only be for partners of HIV infected people? In the United States would the drug only be aimed at the entire population or only at high risk populations, such as minority communities? The same communities who currently have little access to healthcare and could most likely not afford such a long-term drug treatment? In order for PrEP to have the widespread positive impact it has the potential to have, it needs to be handled with caution. PrEP needs to be marketed not as a “cure” for AIDS but as a tool to be used in combination with condoms and other prophylactic treatments to curb the spread of the disease. PrEP also needs to be distributed in populations where it will do the most good and for little or no cost to the user. The HIV/AIDS pandemic shows no signs of stopping and the more ammunition we have to combat the disease the better.