Effectiveness of combination packages for HIV-1 prevention in sub-Saharan Africa depends on partnership network structure: a mathematical modelling study.
OBJECTIVE
Combination packages for HIV prevention can leverage the effectiveness of biomedical and behavioural elements to lower disease incidence with realistic targets for individual and population risk reduction. We investigated how sexual network structures can maximise the effectiveness of a package targeting sexually active adults in sub-Saharan Africa (SSA) with intervention components for medical male circumcision (MMC) and sexual partnership concurrency (having >1 ongoing partner).


METHODS
Network-based mathematical models of HIV type 1 (HIV-1) transmission dynamics among heterosexual couples were used to explore how changes to MMC alone and in combination with changes to concurrency impacted endemic HIV-1 prevalence and incidence. Starting from a base model parameterised from empirical data from West Africa, we simulated the prevalence of circumcision from 10% to 90% and concurrency was modelled at four discrete levels corresponding to values observed across SSA.


RESULTS
MMC and concurrency could contribute to the empirical variation in HIV-1 disease prevalence across SSA. Small reductions in concurrency resulted in large declines in HIV-1 prevalence. Scaling up circumcision in low-concurrency settings yields a greater relative benefit, but the absolute number of infections averted depends on both the circumcision coverage and baseline incidence. Epidemic extinction with this package will require substantial scale-up of MMC in low-concurrency settings.


CONCLUSIONS
Dynamic sexual network structure should be considered in the design and targeting of MMC within combination HIV-1 prevention packages. Realistic levels of coverage for these packages within southern Africa could lead to a reduction of incidence to the low levels observed in western Africa, and possibly, epidemic extinction.
Department of Epidemiology, Emory University, Atlanta, Georgia, USA.
Samuel M
SM
Jenness
Department of Anthropology, University of Washington, Seattle, Washington, USA.
Steven M
SM
Goodreau
Departments of Statistics & Sociology, University of Washington, Seattle, Washington, USA.
Martina
M
Morris
Department of Geography, University of California, Santa Barbara, California, USA.
Susan
S
Cassels
D017954:Africa South of the Sahara / Q000453:epidemiology; D002944:Circumcision, Male / Q000706:statistics & numerical data; D003153:Community Health Services / Q000458:organization & administration; D018450:Disease Progression; D015658:HIV Infections / Q000517:prevention & control* / Q000635:transmission; D006293:Health Promotion; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D015995:Prevalence; D015397:Program Evaluation; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012747:Sexual Partners; D012944:Social Support
AFRICA; MATHEMATICAL MODEL; PREVENTION; SEXUAL BEHAVIOUR; SEXUAL NETWORKS