Table 1 Summary of risk factors for COVID-19 in people affected by SUD

• A protective effect of nicotine has been claimed, but a systematic review (5 studies, n = 1358) has shown that smoking is associated with adverse outcomes of COVID-19. Another study (169 hospitals, n = 8910) found the risk of death for current smokers during hospitalization due to COVID-19 79% higher than in non-smokers.

• Alcohol use, especially heavy use, weakens the innate and acquired immune systems, thus increasing the risk of infections such as tuberculosis, HBV, HCV, HIV-AIDS, or COVID-19, and worsening the course of the disease. Heavy drinking is a well-established risk factor for acute respiratory distress syndrome.

• Regular cannabis use is associated with coughing and other respiratory symptoms.

• Lung injuries related to vaping and/or smoking.

• Lack of access to hand washing, disinfecting wipes, and personal protective equipment (PPE), and overcrowding among certain groups of people who use drugs (e.g., those in incarceration, homelessness).

• Pulmonary hypertension associated with methamphetamine use.

• Compromised immune function.

• Stigma of drug and alcohol use as a barrier to accessing healthcare.

• Sharing cigarettes, drinks, or needles is high-risk behaviors for becoming infected with SARS-CoV-2.

• Lockdown has had an impact on illicit drug supplies, with a subsequent impact on behaviors of people who use substances.