Transforming social structures and environments to help in HIV prevention.

Interest in social and structural interventions for HIV prevention is growing. Such approaches modify social norms, institutions, laws, and policies to reduce vulnerability and create environments in which individuals can protect themselves against HIV infection. Examples include expanding access to sterile syringes for injecting drug users and subsidizing stable housing for low-income people. Evidence of the effectiveness of such interventions is emerging despite scientific and political obstacles to their development, implementation, and evaluation. The U.S. government can help build the evidence base for such interventions. It can also implement those with demonstrated or promising results as part of a cost-effective HIV prevention strategy domestically and globally.