Understanding the HIV Epidemic Among MSM in Baltimore: A Modeling Study Estimating the Impact of Past HIV Interventions and Who Acquired and Contributed to Infections

Abstract

Introduction: Men who have sex with men (MSM) in the United States are disproportionately affected by HIV. We estimated the impact of past interventions and contribution of different population groups to incident MSM HIV infections. Setting: Baltimore, US. Methods: We used a deterministic model, parameterized and calibrated to demographic and epidemic Baltimore MSM data, to estimate the fraction of HIV infections among MSM averted by condoms and antiretroviral therapy (ART) over 1984-2017 and the fraction of infections acquired and transmission contributed by MSM from different demographic groups and disease and care continuum stages over 10-year periods from 1988 to 2017, using population attributable fractions. Results: Condom use and ART averted 19% (95% uncertainty interval: 14%-25%) and 23% (15%-31%) of HIV infections that would have occurred since 1984 and 1996, respectively. Over 2008-2017, 46% (41%-52%) of incident infections were acquired by and 35% (27%-49%) of transmissions contributed by MSM aged 18-24 years (who constitute 27% of all MSM, 19% of HIV+ MSM). MSM with undiagnosed HIV infection, those with diagnosed infection but not in care, and those on ART contributed to 41% (31%-54%), 46% (25%-56%), and 14% (7%-28%) of transmissions, respectively.

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

“…Reflecting this setting of low HIV incidence, high ART coverage, and low AIDS incidence, our model suggests that those in the acute infection stage have contributed a relatively larger proportion of transmission events over the last decade. These estimates are comparable with estimates found among gbMSM in the UK (population attributable fraction: 3-28% in 2014-15) 15 and Baltimore (8-35% over 2008-17) 11 . Given the heightened HIV transmissibility during the primary stage of infection 47 , identifying new clusters of infections through the routine use of recency assays 48 , phylogenetic testing 49 , and genetic sequencing 50 could help achieve HIV elimination.…”

“…Tools such as agent-based models (ABM) –computer simulations of epidemics– are appropriate to understand and characterize past and future transmission dynamics 10 . Mathematical models of HIV transmission have been used to describe the drivers (e.g., age, infection stage, knowledge of status, and treatment status 11,12 ) and dynamics of global and local HIV epidemics. These models have focused on different population subgroups, have been applied to a range of geographical locations, and have studied, both prospectively and retrospectively, the impact of various interventions on HIV dynamics 13-16 .…”

Quantifying the Evolving Contribution of HIV Interventions and Key Populations to the HIV Epidemic in Yaoundé, Cameroon

“…) 55 (indicator 4). To identify where these direct and indirect transmissions occurred, HIV transmission rates were also calculated as the number of infections due to the specific risk group over [t0, t] occurring in another specific group.…”

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

“…Tools such as agent-based models (ABM) -computer simulations of epidemics-are appropriate to understand and characterize past and future transmission dynamics [9][10][11][12]. Mathematical models of HIV transmission have been used to describe the drivers (e.g., age, infection stage, knowledge of status, and treatment status [14,15]) and dynamics of global and local HIV epidemics. These models have focused on different population subgroups, have been applied to a range of geographical locations, and have studied, both prospectively and retrospectively, the impact of various interventions on HIV dynamics [11,[16][17][18].…”