CROI 2013: New tools to understand transmission dynamics and prevent HIV infections.

New tools to track HIV incidence and identify transmission networks are providing insights about the leading edge of new HIV infections globally. Phylogenetic analyses point to the continued global nature of HIV transmission patterns and the challenges to reducing HIV infections through targeted antiretroviral programs alone. New methods for measuring acute infection and HIV incidence using cross-sectional surveys are proving useful in tracking the impact of prevention programs at the population level. Globally, men who have sex with men, and young men and women continue to be at highest risk of HIV acquisition; the US South also bears a disparate burden of new HIV infections and poor HIV-related outcomes. The use of injectable hormonal contraception may increase HIV acquisition risk; new, effective contraceptive methods and contraceptive counseling are needed, as simply removing this strategy could lead to a net increase in deaths due to unintended pregnancies. Another preexposure prophylaxis efficacy trial failed to show protection, likely because of poor adherence by women in the trial. Fortunately, new strategies are being developed that could substantially reduce new infections globally, such as methods to increase adherence and the use of long-acting antiretroviral agents.