The purpose of RethinkHIV is to identify and highlight the most cost-effective responses to HIV/AIDS in sub-Saharan Africa (SSA) with economic analyses of the benefits and costs of specific interventions in six categories of responses to HIV/AIDS. This is the assessment paper on the first of the six topics: prevention of sexual transmission of HIV.

As is well-known, sexual infections are a major source of the spread of HIV/AIDS generally (UNAIDS 2010), and are thought to be by far the most important source of the spread of HIV/AIDS in SSA, though there also are other sources of spread of the disease, such as maternal-child infection and the use of contaminated blood or needles. Sexual interactions may directly result in the transmission of HIV, and they also may increase the vulnerability to the HIV virus through transmitting other sexually transmitted diseases. Interventions to reduce sexual infections broadly speaking can work through reducing the frequency of such interactions or through reducing the risks of sexual infection per sexual encounter. Selection of partners, including with respect to age and risk behavior of the partner, condom use or other risk reduction strategies with a specific partner, and biomedical interventions that affect HIV transmission can all affect HIV infection risks. Interventions have been proposed to work through both of these channels, though with greater emphasis probably on the latter.