Implications of all the available evidence
generalised
VIRUS
The heterosexual HIV epidemic in sub-Saharan Africa appears to be maintained by transmissions from young women and slightly, but not substantially, older men. The contributions of sources transmitting drug-resistant virus, or sources who reside outside a focal community, are not particularly large, and there is no disproportionate contribution from individuals who share any combination of a high-risk age group, a residence outside the community, and drug-resistant virus.In generalised HIV epidemics, it is tempting to attempt to identify particular demographic groups, of relatively small sizes, for whom intensive targeting of prevention measures will have a major effect on transmission in the general population. The current state of the evidence suggests that this might not be possible, with transmission coming most frequently from younger individuals, disproportionately men, whose demographics are otherwise quite typical of their community. While it might be more difficult and resource-intensive to design universal interventions for the whole population, there can be no shortcuts.The HPTN 071 (PopART) cluster-randomised trialThe HPTN 071-02 (PopART) Phylogenetics Study was set up in the Zambian communities of HPTN 071. It aimed to use viral genomes to characterise sources of ongoing transmission, assess the effectiveness of the intervention had it been rolled out nationwide, and identify the most promising policies for prevention in the future.HIV phylogenies can reconstruct the demographic and spatial history of transmission. In population-level analyses, phylogenetic inference has been used to describe the origin and global spread of HIV,Recent methodological innovations in phylogenetics have made it possible, in large studies with high sampling density and after de-identification, to identify probable transmission pairs.