CDC Trials of Pre-Exposure Prophylaxis for HIV Prevention

New approaches to HIV prevention are urgently needed to stem the estimated 2.7 million new HIV infections that occur worldwide each year. While behavior change programs have contributed to dramatic reductions in the number of annual infections in the United States and many other nations, far too many individuals remain at high risk. With an effective vaccine years away, there is mounting evidence that antiretroviral drugs may be able to play an important role in reducing the risk of HIV infection. As part of its commitment to developing new HIV prevention strategies, the Centers for Disease Control and Prevention is sponsoring clinical trials of pre-exposure prophylaxis, or PrEP, for HIV prevention. The trials test the antiretroviral drug tenofovir disoproxil fumarate (or tenofovir, brand name Viread®) used alone or in combination with emtricitabine (together, known as the brand name Truvada®) taken as a preventative drug.

CDC is involved in several clinical trials that are designed to answer important questions about the safety and efficacy of a tenofovir or tenofovir plus emtricitabine pill taken as a daily oral HIV preventative among populations at high risk for infection. CDC is sponsoring trials examining PrEP among heterosexuals in Botswana and injection drug users in Thailand. The trial in Thailand is a safety and efficacy trial, while the Botswana trial is examining clinical and behavioral safety and adherence. CDC also co-manages two trial sites in Uganda as part of the University of Washington Partners PrEP Study to examine the safety and efficacy of PrEP among heterosexual couples in which one partner is infected and the other is not. The Botswana, Thailand, and Uganda trials are all assessing the effects of taking a daily pill on HIV risk behaviors, adherence to and acceptability of the regimen, and in cases where participants become HIV-infected, the resistance characteristics of the acquired virus. This information will be critical to guide future studies and HIV prevention programs.

In 2010, CDC completed the first study to examine the safety of daily tenofovir for HIV prevention among MSM in the United States. Preliminary analyses suggest no serious safety concerns. Additional analyses are underway.