Combination prevention to achieve significant reductions in HIV incidence: projections of the impact of microbicide and male circumcision interventions in rural Uganda

Background: Male circumcision (MC) has been shown to prevent male HIV acquisition. Female initiative products, such as microbicides, are in development. There is an increasing focus on ARV based products, that could protect women from HIV acquisition. These two forms of intervention could potentially be very complementary, yet their value in combination has not been explored. We simulate the potential impact of MC and microbicide interventions singularly and in combination in a rural Ugandan setting.
Methods: A dynamic HIV model was fitted to rural Ugandan HIV using setting specific behavioural data, and used to estimate the impact on HIV transmission of a microbicide and/or MC intervention over 15 years. The efficacy of MC was assumed to be 60% per sex act (protecting only males) with intervention coverage increasing linearly from existing levels (18%) to reach a final coverage of 48% at 10 years. Microbicides were assumed to have an efficacy of 60% per sex act (protecting only females), consistency of use of 80% with coverage increasing linearly from 0 to 30% over 10 years.
Results: The MC intervention alone resulted in a 12% relative reduction in incidence (RRI) over 15 years. Microbicides led to a 8.4% RRI. In combination there was a 20% RRI. In order to achieve a 20% RRI using one intervention would require a population coverage of at least 64% for microbicides and for MC would require raising the prevalence of MC from 18% to 65%.
Conclusions: Individually it is unlikely that either of these interventions could achieve 20% RRI without attaining coverage in excess of 60%. An integrated approach using complementary interventions may prove to be a more practical approach to achieving substantial reductions in HIV incidence.

A. Cox1, A. Foss1, L.-A. Schafer2, R. Nsubuga2, P. Vickerman1, R. Hayes3, C. Watts1, R. White3
1London School of Hygiene & Tropical Medicine, Public Health and Policy, London, United Kingdom, 2Medical Research Council / Uganda Virus Research Institute, Entebbe, Uganda, 3London School of Hygiene & Tropical Medicine, Epidemiology and Population Health, London, United Kingdom