This is an academic article that discusses why people who use drugs are at increased risk for exposure to COVID-19, due to structural and social challenges, and why this population is at increased risk for a more severe course of the virus, primarily due to comorbidities.
Walters, S.M., Seal, D.W., Stopka, T.J., Murphy, M.E., Jenkins, W.D. (2020). COVID-19 and People Who Use Drugs - A Commentary. Health Behavior and Policy Review, 7(5), 489-497.