Abstract
This paper examines the ways in which HIV prevention is understood including "biomedical", "behavioural", "structural", and "combination" prevention. In it I argue that effective prevention entails developing community capacity and requires that public health addresses people not only as individuals but also as connected members of groups, networks and collectives who interact (talk, negotiate, have sex, use drugs, etc.) together. I also examine the evaluation of prevention programmes or interventions and argue that the distinction between efficacy and effectiveness is often glossed and that, while efficacy can be evaluated by randomized controlled trials, the evaluation of effectiveness requires long-term descriptive strategies and/or modelling. Using examples from a number of countries, including a detailed account of the Australian HIV prevention response, effectiveness is shown to be dependent not only on the efficacy of the prevention technology or tool but also on the responses of people - individuals, communities and governments - to those technologies. Whether a particular HIV prevention technology is adopted and its use sustained depends on a range of social, cultural and political factors. The paper concludes by calling on biomedical and social scientists to work together and describes a "social public health".