A rigorously-designed trial of universal testing and treatment ( UTT ) interventions is needed because : i ) it is unknown whether these interventions can be delivered to scale with adequate uptake ; ii ) there are many uncertainties in the models such that the population-level impact of these interventions is unknown ; and ii ) there are potential adverse effects including sexual risk disinhibition , HIV-related stigma , over-burdening of health systems , poor adherence , toxicity , and drug resistance.In the HPTN 071 ( PopART ) trial , 21 communities in Zambia and South Africa ( total population 1.2 m ) will be randomly allocated to three arms .