A universal HIV testing-and-treatment (UTT) approach has been shown to be effective as an intervention in high prevalence areas in sub-Saharan Africa (SSA) to reduce HIV incidence. Community-wide interventions may change the dynamics of the epidemic. Understanding these changes will inform future policy towards achieving zero new infections. Using an individual-based model (PopART-IBM), developed as part of the HPTN 071 (PopART) trial, we project the impact of four scenarios of UTT to 2030 on the distribution of incident cases stratified by categories of sexual risk-taking behaviour.
Model predictions were made with the PopART-IBM calibrated to data from a representative trial community in Zambia from the HPTN 071 (PopART) trial. The model has been previously validated against the primary endpoint of the trial. The model separates the population into three groups according to sexual risk-taking behaviour based on behavioural questionnaire data, including number of sex partners and use of condoms. The proportions of individuals in each risk group (low 50%, medium 35%, high 15%) were assumed to be static through time. Model projections to 2030 are based on four scenarios: 1) PopART then continuation of UTT in the PopART community; 2) PopART then no UTT; 3) no PopART but nationwide UTT from 2020; 4) no PopART and no UTT.
Making antiretroviral therapy universally accessible to all who are HIV-positive in the PopART community would lead to a decline in prevalence in all risk groups but would concentrate new cases in those with the highest levels of risk-taking behaviour (65% of incident cases vs 54% if no UTT was implemented; figure 1). While population HIV incidence to 2030 decreases, the model predicts continued persistence of an HIV epidemic in the high-risk subpopulation in all scenarios unless nationwide UTT is adopted.
Our results predict that even with a UTT intervention, the proportion and absolute number of new HIV cases in those with the highest levels of sexual risk-taking behaviour would increase, despite overall HIV prevalence decreasing. Our results highlight that targeting of high-risk individuals may be necessary following successful UTT interventions in order to eliminate HIV as a public health issue in SSA.