Background: Many ways of preventing HIV infection have been proposed and more are being developed. We sought to construct a strategic approach to HIV prevention that would use limited resources to achieve the greatest possible prevention impact through the use of interventions available today and in the coming years.
Methods: We developed a mathematical model of the HIV epidemic in South Africa and formed assumptions about the costs and effects of a range of interventions, encompassing the further scale-up of existing interventions (promoting condom use, male circumcision, outreach testing and early ART initiation for all, and oral PrEP), the introduction of new interventions in the medium-term (offering intravaginal rings (IVR), long-acting antiretrovirals (LA-ARVS)) and long-term (vaccine, broadly neutralising antibodies (bNAbs)). We examined how available resources could be allocated across these interventions to achieve maximal impact, and assessed how this would be affected by the failure of the interventions to be developed or scaled up.
Findings: If all the above-listed interventions are available, the optimal mix of interventions would place great emphasis on: (i) scale-up of male circumcision and outreach testing and ART initiation, as these are available immediately and are assumed to be low cost and/or highly efficacious; (ii) IVR targeted to sex workers; and (iii) vaccines, as these can achieve a high impact if scaled-up even if imperfectly efficacious. It would rely less on longer-term developments, such as LA-ARVS and bNAbs, unless the costs of these reduced. However, if it were not possible to scale up existing interventions to the extent assumed, greater emphasis would be placed on oral PrEP, IVR and LA-ARVs. The long-term impact on the epidemic is most affected by scale-up of existing interventions and the successful development of a vaccine.
Interpretation: With current information, a strategic approach in which limited resources are used to maximise prevention impact would focus on strengthening the scale-up of existing interventions, whilst pursuing a workable vaccine and developing other approaches that can be used if further scale-up of existing interventions is limited.