What works, and what remains to be done, in HIV prevention in the United States.

Since the beginning of the HIV epidemic in the United States, HIV prevention programs have prevented hundreds of thousands of HIV infections, and the investment in these programs has actually been cost-saving to society in terms of medical costs averted. A substantial body of evidence exists (including randomized controlled trials and careful meta-analyses) which demonstrates that various HIV prevention services are effective; an increasingly large body of data also demonstrates the cost-effectiveness of these interventions. However, the efforts to utilize these interventions in a comprehensive HIV prevention program are hampered by insufficient funding, imperfect targeting strategies, and a problematic policy environment that creates barriers to the use of some of these life-saving interventions. Progress toward reducing new HIV infections will likely be as much a function of improvements in funding and policies as it will in the development of new tools for HIV prevention.