Prospects for HIV control in South Africa: a model-based analysis

Abstract

BackgroundThe goal of virtual elimination of horizontal and mother-to-child HIV transmission in South Africa (SA) has been proposed, but there have been few systematic investigations of which interventions are likely to be most critical to reducing HIV incidence.ObjectiveThis study aims to evaluate SA's potential to achieve virtual elimination targets and to identify which interventions will be most critical to achieving HIV incidence reductions.DesignA mathematical model was developed to simulate the population-level impact of different HIV interventions in SA. Probability distributions were specified to represent uncertainty around 32 epidemiological parameters that could be influenced by interventions, and correlation coefficients (r) were calculated to assess the sensitivity of the adult HIV incidence rates and mother-to-child transmission rates (2015–2035) to each epidemiological parameter.ResultsHIV incidence in SA adults (ages 15–49) is expected to decline from 1.4% in 2011–2012 to 0.29% by 2035 (95% CI: 0.10–0.62%). The parameters most strongly correlated with future adult HIV incidence are the rate of viral suppression after initiating antiretroviral treatment (ART) (r=−0.56), the level of condom use in non-marital relationships (r=−0.40), the phase-in of intensified risk-reduction counselling for HIV-positive adults (r=0.29), the uptake of medical male circumcision (r=−0.24) and the phase-in of universal ART eligibility (r=0.22). The paediatric HIV parameters most strongly associated with mother-to-child transmission rates are the relative risk of transmission through breastfeeding when the mother is receiving ART (r=0.70) and the rate of ART initiation during pregnancy (r=−0.16).ConclusionsThe virtual elimination target of a 0.1% incidence rate in adults will be difficult to achieve. Interventions that address the infectiousness of patients after ART initiation will be particularly critical to achieving long-term HIV incidence declines in South Africa.

The cost‐effectiveness of multi‐purpose HIV and pregnancy prevention technologies in South Africa

“…These estimates of cost-effectiveness are broadly comparable to published studies, though there is considerable heterogeneity in these [20]. Although we base our counterfactual scenario on empirical data from trials and nationally representative population based studies, our simple incidence model predicts a higher number of annual infections than more complex models, such as Thembisa and EPP/Spectrum models [58,59]. The reason for this is uncertain, although it is worth noting that the both models underestimate the 2012 HIV incidence in South Africa compared to empirical estimates by around 0.4 infections/100 person years among women aged 16-29 [60].…”

Producing HIV estimates: from global advocacy to country planning and impact measurement

“…The Spectrum/AIM module can incorporate the AEM incidence estimates and produce the standard UNAIDS estimates. Models that are made specifically for a country, such as the Thembisa model from South Africa [63], provide more finely tuned country-specific estimates. These models also provide useful information and comparisons for the UNAIDS estimates [55].…”

Population-level HIV incidence estimates using a combination of synthetic cohort and recency biomarker approaches in KwaZulu-Natal, South Africa

“…Several alternative approaches have been proposed for estimating HIV incidence, including a 'synthetic cohort' approach -i.e. inferring incidence from the age and/or time structure of prevalence [1][2][3][4][5][6], from biomarkers for 'recent infection' measured in cross-sectional surveys [7][8][9][10][11], or using dynamical population models that have been calibrated to survey data [12][13][14][15]. No single method by itself achieves the desired levels of accuracy and precision [16].…”