Attaining realistic and substantial reductions in HIV incidence: model projections of combining microbicide and male circumcision interventions in rural Uganda
- Andrew P Cox1,
- Anna M Foss1,
- Leigh Anne Shafer2,
- Rebecca N Nsubuga2,
- Peter Vickerman1,
- Richard J Hayes3,
- Charlotte Watts4,
- Richard G White5
- 1Social and Mathematical Epidemiology Group, Centre for Mathematical Modelling of Infectious Disease, London School of Hygiene and Tropical Medicine, London, UK
- 2Medical Research Council, Uganda Virus Research Institute, Uganda Research Unit on AIDS, Entebbe, Uganda
- 3Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
- 4Social and Mathematical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
- 5Department of Infectious Disease Epidemiology and Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, UK
- Correspondence to Dr Andrew Paul Cox, London School of Hygiene and Tropical Medicine, 15–17 Tavistock Place, London WC1H 9SH, UK;
Contributors APC adapted the mathematical model with help from PV, conducted the mathematical modelling, collaborated in the design of the study and co-led the drafting of the manuscript. AMF provided technical input into the mathematical modelling, collaborated in the design of the study and collaborated in the drafting of the manuscript. LAS co-led the study, conducted statistical analyses, collaborated in the design of the study and commented on revisions of the manuscript. RNN conducted statistical analyses and commented on revisions of the manuscript. PV wrote the original mathematical model, provided technical input into the mathematical modelling and commented on revisions of the manuscript. RJH co-led the study, collaborated in the design of the study and commented on revisions of the manuscript. CW commented on revisions of the manuscript and collaborated in the design of the study. RGW co-led the study, provided technical input into the mathematical modelling, collaborated in the design of the study and co-led the drafting of the manuscript.
- Accepted 22 June 2011
- Published Online First 18 July 2011
Objectives This study simulates the potential impact of male circumcision and female microbicide interventions, singularly and in combination, in rural Uganda.
Methods A dynamic model was parameterised and fitted to setting-specific data, and used to estimate the impact on HIV transmission of a microbicide and/or male circumcision intervention over 15 years. The proportion of circumcised men or women using microbicides was assumed to increase linearly from 0.18 (male circumcision) or 0.00 (microbicide use) to the final proportion 10 years later, then remain constant for 5 years. Women using microbicides were assumed to use the product in 80% of penile–vaginal sex acts. Male circumcision or microbicide use was assumed to reduce the per-act probability of HIV acquisition in men or women, respectively, by 60%.
Results Independently, to obtain a 30% relative reduction in HIV incidence at 15 years, the model suggests that the final proportion of women using microbicides would need to be 0.91 (95% CI 0.75 to 1.00) or the proportion of circumcised men would need to be 0.96 (0.83 to impact not possible). The same impact could be achieved by combining the interventions, eg, if the proportion of women using microbicides was 0.49 (0.39 to 0.56) and the proportion of circumcised men was 0.67 (0.57 to 0.74).
Conclusions Under these assumptions, as separate interventions it is unlikely that increases in either the proportion of men circumcised or of women using microbicides could reduce HIV incidence by 30% or more at 15 years. A combination-prevention strategy using complementary interventions may be a more feasible approach to achieve substantial reductions in incidence.
- male circumcision
- mathematical model
- mathematical modelling
Funding This work was supported by the UK Medical Research Council (G0501499) (RGW, APC, LAS, RNN, RJH), the Wellcome Trust (GR078499MA) (RGW, LAS, RNN, RJH) and the Bill and Melinda Gates Foundation (RGW). APC, AMF, PV, RJH and CW are also members of the DFID-funded Knowledge Programme on HIV/AIDS and STI and the Research Programme Consortium for Research and Capacity Building in Sexual and Reproductive Health and HIV in Developing Countries of the LSHTM. This research contributes to the Microbicides Development Programme (MDP). MDP is a partnership of African, UK and Spanish academic/government institutions and commercial organisations. MDP is funded by the British government Department for International Development and the UK Medical Research Council. This research project was also conducted in conjunction with the International Partnership for Microbicides, funded by the European Union.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.