FIGURE 1.

Schematic outline of the cluster-randomization approach used in HPTN 071 (PopART). Three communities with similar characteristics (eg, HIV prevalence; urban, periurban, or rural) were then randomized into study arms A, B, or C. Four clusters of 3 communities in Zambia and 3 clusters of 3 communities in South Africa were randomized. Within each community, an estimated 15,000–30,000 people resided from whom an average of 1832 persons were enrolled into the population cohort from which incidence was measured. Figure adapted from Refs. 44, 81.