COVID-19 and Mental Health (CMH) Initiative: Research

Rapid Review of the Impacts of “Big Events” On People Who Use Drugs and Delivery of Harm Reduction and Drug Treatment Services: Implications for Strengthening Systems in Response to COVID-19

Key Messages

  • Several key indicators were identified for monitoring as the pandemic progresses and evolves, including drug overdose mortality, hepatitis C notifications, and fentanyl availability
  • Flexibility in service provision is critical during and after Big Events. For treatment services, maintaining communication is also important
  • Service providers should be aware of potential trauma as a result of Big Events; in the COVID-19 context, this may include mental health problems and grief
  • Services should maintain up-to-date emergency preparedness plans that refer to a range of potential emergencies
  • There is almost a complete lack of literature to inform responses to particular populations of people who use drugs, including women, Indigenous peoples, and visible minorities. This should be a research priority.

Lay Summary

Big Events generally lead to riskier drug use environments by disrupting drug markets, which in turn affects drug price, purity and availability. As people who use drugs respond and adapt to these changes, risk of harm may increase. For example, changes in suppliers and drugs used may increase overdose risk given that the purity and effects of new drugs may be unknown or unexpected. Drug scarcity may increase violence within the social milieu. If a given Big Event causes harm reduction services to close, people may be more likely re-use and share needles and syringes, increasing their risk of blood borne viral infection. Several studies noted that increased risk behavior sometimes continued after a Big Event had resolved. Critically, these effects are not consistent across Big Events, but vary due to unknown factors.

Publications that provided information on the delivery of harm reduction and drug treatment services discussed responses to the challenges posed by Big Events, and the resources required for services to respond adequately. The impacts of Big Events on service delivery were different between those events that cause widespread disruptions, and those that represent a shock only to the illicit drug market. Big Events can cause changes in treatment demand and retention, although there were mixed findings on the direction of these effects. Service providers may need to be prepared to provide harm reduction and treatment services for drugs that have not previously been widely used in their local area, and for different populations of people who use drugs. Treatment outcomes were better for clients of services that were able to respond flexibly within their clinical guidelines and maintained lines of communication with clients during the crisis. Adequate funding, space, staffing, transportation, training, and preparedness all play a role in maintaining service delivery during and after a Big Event.


  • People who use drugs
  • People who inject drugs
  • Harm reduction
  • Opioid agonist treatment
  • COVID-19
  • Big Events


  • Nominated Principal Applicant: Dr. Sarah Larney, Université de Montréal
  • Professor Julie Bruneau, Université de Montréal and Centre de Recherche du CHUM
  • Professor Marie-France Raynault, Université de Montréal and Centre de Recherche du CHUM
  • Ms. Julie-Soleil Meeson, Association des intervenants en dépendance du Québec
  • Dr. Stine Høj, Centre de Recherche du CHUM,
  • Ms. Nanor Minoyan, Centre de Recherche du CHUM,
  • Ms .Camille Zolopa, Centre de Recherche du CHUM,
  • Ms. Iuliia Marakenko, Centre de Recherche du CHUM

For more information, please contact: Dr. Sarah Larney,

Related Syntheses


Full PDF


People Who Use Drugs (PWUD) and Substance Use


To ensure the rapid dissemination of this critical information, information is published in the language in which it was submitted. Please contact us for French or English translations.

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