Today, the New England Journal of Medicine published research findings from the iPrEx study funded by the National Institutes of Health (NIH) and the Bill and Melinda Gates Foundation testing the efficacy of pre-exposure prophylaxis (PrEP). The study is a major step forward in our ability to prevent new HIV infections. The study found that a daily dose of an oral antiretroviral drug taken by HIV-negative gay and bisexual men and transgender women reduced the risk of acquiring HIV infection by 43.8 percent. The data showed even higher levels of protection from infection, up to 73 percent, among those participants who adhered most closely to the daily drug regimen.
This study is the first of its kind and we will need to validate these findings with other research, much of which is currently underway. There are still a lot of unanswered questions, such as whether this approach is effective in other populations. We also need to examine whether PrEP works effectively with other antiretroviral medications. There are also critical questions about when and for how long individuals need to take these medications and how to combine PrEP with other prevention tools to achieve maximum results. We also need to better understand how to exploit the promise of PrEP without sending signals that lead individuals to stop using condoms or taking other steps that may increase their risk of becoming infected with HIV.
Today, however, is a day to rejoice in these exciting results. What is particularly encouraging for many people is that this study was proven effective in gay and bisexual men - the group responsible for more than half of all new HIV infections in the United States and the only group where HIV incidence has been rising in recent years. We all hope that this will be shown to work for heterosexuals, people who inject drugs, and others. These results also compliment the promising study results announced at the International AIDS Conference in July from the CAPRISA study that demonstrated the efficacy of one of the two drugs used in the iPrEx study (tenofovir) when used as a vaginal microbicide. The findings from these two studies showing that antiretroviral therapy can prevent infection in HIV negative individuals is particularly encouraging given the President’s goal of lowering the annual number of new infections by 25% over the next five years. Although no single HIV prevention strategy is 100 percent effective, today’s findings suggests that antiretroviral medication may play an important role in developing the most effective combination of approaches to prevent HIV.
In commenting today on these promising results, President Obama said the following,
I am encouraged by this announcement of groundbreaking research on HIV prevention. While more work is needed, these kinds of studies could mark the beginning of a new era in HIV prevention. As this research continues, the importance of using proven HIV prevention methods cannot be overstated.
Jeffrey S. Crowley is the Director of the Office of National AIDS Policy