Recent data from HIV prevention trials conducted with sero-discordant couples suggest that HIV transmission drops when the infected individual is taking anti-retroviral medications (ARV). However, there is potential for unintended social and behavioural consequences of this and other interventions. Using the HIV treatment cascade as a lens, the review will cover individual and population-level data in HIV and STD prevention research with a view to identifying such consequences of intervention. Although the focus will be upon risk compensation as a potential consequence of HIV treatment, the review will also attend to potential positive social and behavioural consequences.

With respect to data from which to predict social and behavioural consequences, the majority of HIV and STD prevention interventions are conducted through small groups or on a one-to-one basis (e.g., in clinical settings), rather than at the population level. Most are concerned explicitly with risk reduction behaviours or address the behaviours essential to successful biomedical intervention. Population-level interventions are rarer, but do include communication campaigns and efforts to affect HIV or STD through social determinants. With respect to risk compensation, some studies explicitly address risk compensation, while others have sufficient behavioural follow-up data from which to measure it - the unintended measurement of unintended consequences. Fewer studies permit one to attribute effects to different potential causes of risk compensation, including risk homeostasis, overestimation of protection, or the intentional resumption of previous behaviour patterns.

The final part of the review is devoted to approaches that seek to minimise negative consequences or to maximise positive consequences, the latter arising when an intervention gives people hope where they once had little or none, and leading to further individual efforts to protect themselves and others (including changes in risk homeostasis). Positively-framed communication campaigns in particular may accelerate efforts and further population-level protective action and health promotion.