The future of HIV prevention.

In the decades since the emergence of HIV, numerous approaches to prevent transmission have been tested with varying degrees of success. Because a highly effective vaccine will not be available within the next decade, it is increasingly clear that preventing new HIV infections will require successful implementation of promising behavioral and biomedical interventions in combination. These prevention packages must be sufficiently flexible to include a variety of evidence-based interventions that serve each dynamic population they target, particularly those who are most vulnerable. To optimize the impact of combination intervention packages, well-designed implementation science studies are vital. Efficacy in a clinical trial does not necessarily translate to effectiveness at the population-level, and prioritized research studies should investigate programmatic implementation and operations scale-up and new methods to monitor and evaluate these processes both for organization and cost-effectiveness. With an estimated 2.7 million people becoming newly infected with HIV in 2010, the prevention of HIV remains an urgent global health priority. Since the emergence of HIV/AIDS more than 30 years ago, the evidence base for HIV prevention has expanded and evolved. Here we explore the status of evidence-based HIV prevention, describing both the continuing challenges and the emerging opportunities to reduce HIV incidence.