Table 3 Summary of findings from peer-reviewed sources on previous disasters

• Disasters create high-risk environments that exacerbate substance use and risk of infectious disease spread [16].

• After disasters, people who resume illicit drug use after a period of abstinence or use of safer supply do so in a higher risk context. Decreased purity of illicit supply has been noted after disasters and fears of scarce supply can result in high risk behaviour like sharing of needles [16, 17].

• Personal impacts such as decreased employment, difficulty accessing basic needs, homelessness, lack of transportation, lack of information on how to access OAT and other supports, discrimination and stigma may result in the use of substances to cope with disaster contexts [16, 17].

• Systems issues such as decreases or redirection in public health spending towards disaster relief, disruption to substance use treatment and disruption to harm reduction services increase risks for PWOUD after disasters [18].

• During and after disasters, psychological and emotional distress increases for both PWOUD and staff of support programs who are also personally experiencing the disaster [19].

• Disruption of services after disasters and increase in homelessness associated with some disasters cause psychiatric distress and may increase substance use [18], and displaced populations that rely on shelters can be met with unprepared or untrained staff [20].

• Disruptions in OAT services, inadequate take home dosing, lack of guest-dosing information at alternate clinic sites put PWOUD at increased risk for negative outcomes after a disaster [19, 21].

• When OAT care is disrupted, people turn to emergency departments for access to OAT medications. However emergency clinicians sometimes face barriers prescribing OAT or lack access to patient dosing information, resulting in inadequate or unsafe prescriptions [21].

• Efforts to ensure access to OAT include: Provision of take home dosing, guest dosing at clinics other than the patients’ usual clinic, delivering/mailing of medication to patients, mobile units and communication strategies (e.g., individual phone calls, hotlines and social media) to keep people informed on how to access treatment [21, 22].

Other supports include:

• Mental health support for fear & anxiety after disasters: lack of increase in illicit drug use attributed to availability of mental health professionals, support groups, and counsellors [23].

• Internet-based modules providing psychoeducation and motivational feedback focused on mental health and substance use issues after a disaster [24].

• Disaster planning that values cultural specificity and needs of people who have disabilities, mental health issues, use substances, or are on OAT to ensure providers, first responders, organizations, and emergency managers are prepared for disaster scenarios [22].

• Formal disaster plans and a central database containing dosing information [21, 22] and coordinated emergency laws [20].