What will it take to decrease the burden of the HIV and STI epidemics among MSM in British Columbia, Canada? A sexual network modeling analysis, combining syndemic theory, to evaluate the impact of behavioural and biomedical interventions for HIV and STI

Gay, bisexual, two-spirited and other men who have sex with men (MSM) are disproportionally affected by the HIV epidemic in high-resource countries. Since 2004, in British Columbia (BC), the proportion of new diagnoses among MSM have plateaued, while those of sexually transmitted infections (STIs), especially syphilis, have been rapidly increasing, consistent with a substantial level of condomless anal intercourse. Today, there are three powerful strategies available to prevent HIV infection among MSM, including: the use of condoms, treatment as prevention (TasP), and pre-exposure prophylaxis (PrEP). In this 5-year study, our key contribution will be to develop a new methodology to forecast the consequences and benefits of emerging programs and policies for HIV and STI prevention among MSM prior to their implementation. This methodology will provide a deep understanding of the heterogeneity in sexual practices within MSM networks over time, enabling a more accurate assessment of the impact of different interventions targeting these networks. The proposed analyses accounts for the role of key factors affecting HIV and STI transmission among MSM, including demographic (e.g., age, income level), psychosocial (e.g., substance abuse, history of partner violence, childhood sexual abuse), and health-related factors (e.g., health status). Our ability to confidentially link administrative databases of all people diagnosed with HIV and at risk of acquiring HIV in BC, and assess surveillance testing data, makes this one of the first interdisciplinary research studies of how co-occurring STIs and risk behaviour are fuelling the HIV epidemic within MSM sexual networks. Importantly, this study will provide highly relevant new information for decision makers to inform resource prioritization and policies as they address the future impact of HIV, STIs and utilization of healthcare resources by HIV infected MSM in BC, Canada and internationally.