Past dynamics of HIV transmission among men who have sex with men in Montréal, Canada: a mathematical modeling study

Rachael M Milwid; Yiqing Xia; Carla M Doyle; Joseph Cox; Gilles Lambert; Réjean Thomas; Sharmistha Mishra; Daniel Grace; Nathan J Lachowsky; Trevor A Hart; Marie-Claude Boily; Mathieu Maheu-Giroux

doi:10.1186/s12879-022-07207-7

Past dynamics of HIV transmission among men who have sex with men in Montréal, Canada: a mathematical modeling study

BMC Infect Dis. 2022 Mar 7;22(1):233. doi: 10.1186/s12879-022-07207-7.

Authors

Affiliations

¹ Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, QC, Canada.
² Direction Régionale de Santé Publique de Montréal, Montréal, QC, Canada.
³ Clinique Médicale L'Actuel, Montréal, QC, Canada.
⁴ Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada.
⁵ Social and Behavioural Health Sciences, Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
⁶ School of Public Health and Social Policy, University of Victoria, Victoria, BC, Canada.
⁷ Department of Psychology, Ryerson University, Toronto, ON, Canada.
⁸ Department of Infectious Diseases, Imperial College London, London, UK.
⁹ Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, QC, Canada. mathieu.maheu-giroux@mcgill.ca.

Abstract

Background: Gay, bisexual, and other men who have sex with men (gbMSM) experience disproportionate risks of HIV acquisition and transmission. In 2017, Montréal became the first Canadian Fast-Track City, setting the 2030 goal of zero new HIV infections. To inform local elimination efforts, we estimate the evolving role of prevention and sexual behaviours on HIV transmission dynamics among gbMSM in Montréal between 1975 and 2019.

Methods: Data from local bio-behavioural surveys were analyzed to develop, parameterize, and calibrate an agent-based model of sexual HIV transmission. Partnership dynamics, HIV's natural history, and treatment and prevention strategies were considered. The model simulations were analyzed to estimate the fraction of HIV acquisitions and transmissions attributable to specific groups, with a focus on age, sexual partnering level, and gaps in the HIV care-continuum.

Results: The model-estimated HIV incidence peaked in 1985 (2.3 per 100 person years (PY); 90% CrI: 1.4-2.9 per 100 PY) and decreased to 0.1 per 100 PY (90% CrI: 0.04-0.3 per 100 PY) in 2019. Between 2000-2017, the majority of HIV acquisitions and transmissions occurred among men aged 25-44 years, and men aged 35-44 thereafter. The unmet prevention needs of men with > 10 annual anal sex partners contributed 90-93% of transmissions and 67-73% of acquisitions annually. The primary stage of HIV played an increasing role over time, contributing to 11-22% of annual transmissions over 2000-2019. In 2019, approximately 70% of transmission events occurred from men who had discontinued, or never initiated antiretroviral therapy.

Conclusions: The evolving HIV landscape has contributed to the declining HIV incidence among gbMSM in Montréal. The shifting dynamics identified in this study highlight the need for continued population-level surveillance to identify gaps in the HIV care continuum and core groups on which to prioritize elimination efforts.

Keywords: Agent-based model; Approximate Bayesian Computation Sequential Monte Carlo; Gay bisexual and other men who have sex with men (gbMSM); HIV/AIDS; Mathematical modeling; Treatment and care cascade.

MeSH terms

Adult
Canada / epidemiology
HIV Infections* / prevention & control
Homosexuality, Male
Humans
Male
Sexual Behavior
Sexual and Gender Minorities*

Grants and funding

MR/R015600/1/MRC_/Medical Research Council/United Kingdom