In response to the novel coronavirus 2019 (Covid-19) pandemic, many people experiencing homelessness and substance use disorders entered respite and recuperation facilities for care and to isolate and prevent subsequent SARS-CoV-2 transmission. However, because drug use was officially prohibited in these facilities, we observed people who use substances leaving isolation temporarily or prematurely. The initial Covid-19 surge magnified the need for harm reduction access for those who use substances to ensure their safety and well-being and that of their local communities. In this commentary, we argue that expanding harm reduction access is crucial for subsequent waves of SARS-CoV-2 infection and also for patients who use substances and are hospitalized for other reasons.