Grant: Travel Awards - Institute Community Support

Identifying HIV transmission risk factors can inform the prioritization of treatment and prevention services. The analysis of patients' HIV sequences can illuminate transmission activity beyond what is visible by traditional epidemiology methods alone. Although identifying clusters of similar HIV sequences is routinely performed to evaluate patient characteristics associated with high transmission activity, using cluster membership alone over-simplifies the range of transmission activity across a population. We introduce an alternative method to investigate HIV transmission risk factors in British Columbia (BC), Canada, based on patients' viral diversification rates. For 8,103 people living with HIV (PLHIV) in BC in March 2018, we recovered the oldest available HIV protease and RT sequences from the BC Drug Treatment Program database. We applied phylogenetics to infer the family history of viral sequences across the population of PLHIV, and then for each viral tip in the tree, we calculated its diversification rate as an estimate of its transmission rate. Patient attributes significantly associated with high viral transmission were evaluated using a generalized linear model. High HIV transmission activity was positively associated with being younger, using injection drugs, having hepatitis C virus, having a high recent viral load, and residing within the Northern BC Health authority. In contrast, having ever had AIDS and identifying as black were both significantly associated with lower transmission activity. By identifying risk factors associated with HIV transmission using the viral diversification rate among PLHIV, we can confidently recommend prioritized provision of treatment and prevention services for key groups. Additionally, these analyses highlight that HIV diversification rates can illuminate differences in individuals' transmission activity, regardless of phylogenetic cluster membership.