Multiple phylogenetic studies of HIV in sub-Saharan Africa have shown that mobility-driven transmission frequently occurs: many communities export and import strains. Mobility-driven transmission can result in source–sink dynamics: one community can sustain a micro-epidemic in another community in which transmission is too low to be self-sustaining. In epidemiology, the basic reproduction number (R₀) is used to specify the sustainability threshold. R₀ represents the average number of secondary infections generated by one infected individual in a community in which everyone is susceptible. If R₀ is greater than 1, transmission is high enough to sustain an epidemic; if R₀ is less than 1, it is not. Here, we discuss the conditions that are needed (in terms of R₀) for source–sink transmission dynamics to occur in generalised HIV epidemics in sub-Saharan Africa, present an example of where these conditions could occur (ie, Namibia), and discuss the necessity of considering mobility-driven transmission when designing control strategies. Additionally, we discuss the need for a new generation of HIV transmission models that are more realistic than the current models. The new models should reflect not only geographical variation in epidemiology and demography, but also the spatial–temporal complexity of population-level movement patterns.

撒哈拉以南非洲对艾滋病毒的多种系统发育研究表明，流动性驱动的传播经常发生：许多社区出口和进口毒株。流动性驱动的传播可能会导致源到汇的动态变化：一个社区可以在另一个社区中维持微流行，因为在该社区中，传播太低而无法自我维持。在流行病学中，基本繁殖数（R ₀）用于指定可持续性阈值。R ₀代表在每个人都易感的社区中，一个被感染个体所产生的平均二次感染数。如果R ₀大于1，则传播足以维持流行。如果R ₀小于1，不是。在这里，我们讨论在撒哈拉以南非洲普遍的HIV流行中发生源-汇传播动态所需的条件（以R _0表示），并举例说明这些条件可能发生的地方（即纳米比亚），以及讨论在设计控制策略时考虑移动性传动的必要性。此外，我们讨论了比当前模型更现实的新一代HIV传播模型的需求。新模型不仅应反映流行病学和人口统计学的地理差异，还应反映人口水平运动模式的时空复杂性。