More than 25 years into the global HIV epidemic, Southern Africa remains the region carrying the highest burden of HIV and AIDS globally. Eight countries in the region have reported an adult prevalence rate in excess of 15 percent. In 2007, 1.5 million new infections occurred in the region accounting for almost 35 percent of all new HIV infections.

Up to 25% of 15-49 year-olds are HIV positive, and the annual incidence in young women is 4-6%. Although some real reductions in HIV prevalence in the region has been achieved by changes in sexual behaviour (see Zimbabwe) and HIV prevalence in young attendees of antenatal clinics has started to decline in most countries, HIV incidence continues to be high. For instance, women and girls account for more than 90 per cent of new infections among 15-24 year olds in South Africa.

HIV transmission in the region occurs mostly within long-term and occasional heterosexual partnerships, often transgressing traditional concepts of high or low risk. Multiple vulnerability and risk factors (such as mobility, gender-based violence, or concurrent partnerships), which individually exist to an even greater extent in other regions (eg, low rates of male circumcision in Europe), act in synergy in these societies.

Even if greater coverage of all effective interventions for HIV prevention is a priority in high-prevalence societies, and would most probably result in large reductions in HIV incidence, individual behaviour change alone is unlikely to stop the spread of HIV in a sustainable way. Comprehensive HIV prevention should urgently include programmes that address the key drivers of the epidemic in the region, in particular those that change societal norms and create safer sexual environments and those that reduce the vulnerability of communities and individuals.

In communities that are heavily affected by HIV, prevention activities must also go hand in hand with treatment and strategies to mitigate effects on individuals, households, and communities. Promotion of HIV prevention without mitigating the overwhelming consequences of the epidemic has little impact and provides few incentives for safe sexual behaviour.

These principles have been put into practice in many settings. For example, in Zambia, the Antiretroviral Community Education and Referral Project, ACER, aimed to bolster positive attitudes to treatment and prevention in communities by employing treatment-support workers and treatment mobilisers. The project has since been extended to Uganda and within Zambia on the basis of its generally positive effects (although project sites and comparisons sites did not differ on most measures, including sexual behaviours). Both operational research and systematic evaluation should urgently try to not only capture the ways in which integrated interventions which tackle social vulnerability can be made more effective, but also measure their effect on HIV-related outcomes, such as quality of life, mortality, and HIV transmission.

The challenge in the hyperendemic context is not so much to specify the content of HIV prevention programmes (with some exceptions such as interventions for serodiscordant couples) but to identify the mechanisms by which these programmes will be implemented at sufficient scale. The substance of HIV prevention has been well developed in the region itself. The difficult challenges are to elevate HIV prevention as a national priority and to deliver on leadership, governance, institutional and community capacity, accountability and implementation in general. Initiation of such a nationwide response has at least three major policy implications: (1) HIV prevention must be an integral part of a country's development plan; (2) multiple sectors in government and civil society must be actively engaged; and (3) the effort must be effectively led at the highest level of the state, as is the case in Botswana.

UNAIDS coordinates its own collective efforts on scaling up prevention, within the ambit of universal access to prevention, care, support and treatment, through building on the comparative advantages of the UNAIDS Cosponsors and Secretariat to support scale up of high quality, comprehensive HIV prevention programmes at all levels. UNAIDS also collaborates with a large number of other stakeholders and promotes and supports the development of strong HIV prevention constituencies. The main focus of UNAIDS on intensification of HIV prevention is at country level as part of its ongoing efforts to support countries to strengthen their overall national responses to the AIDS epidemic.