PROJECT SUMMARY COVID-19 threatens to exacerbate the national opioid crisis by reducing availability and access to harm reduction and health services delivered by syringe service programs (SSPs). Monitoring the impact of COVID- 19 on the availability and delivery of harm reduction and health services by SSPs in the U.S. over time is imperative for guiding local and national opioid policies. Failure to restore services will require additional responses to avoid adverse consequences, including HIV and hepatitis C outbreaks, whereas potentially beneficial responses, such as eliminating 1:1 syringe exchange requirements, should be disseminated widely. This supplement proposes collecting and analyzing longitudinal data on the impact of recovery from COVID-19 on SSPs. We will describe the changes in national SSP services in response to COVID-19 over one year via qualitative interviews and short surveys with SSPs every 6 months. Interviews will explore changes in harm reduction and health services offered; funding, adoption and sustainment of innovative services and service delivery; and barriers and facilitators for SSPs to delivering different services over a year. Descriptive data analysis will be conducted to determine if programs recover, maintain, or adapt services 6 and 12 months after the baseline survey. Qualitative data will be analyzed using content analysis. We will also conduct a longitudinal analysis to determine the associations between COVID-19 reported infections, COVID-19 response policies, and SSP services delivered. SSPs registered with the North American Syringe Exchange Network will be invited to participate in the longitudinal study that will collect monthly data on 1) number of syringes dispensed, 2) number of naloxone kits dispensed, 3) estimated number of participants served (directly and through secondary exchange), and 4) whether the SSP offered any on-site HIV or HCV testing in that month. COVID-19 reported infections and policies will be derived from publicly available data sources. We will conduct interrupted time series analysis to determine if changes in local COVID-19 stay-at-home policies are associated with changes in the monthly number of syringes and naloxone distributed and per client rates, taking into account reported local infection rates. Time-to-event analysis will be used to assess the impact of COVID-19 infection rates and policies on HIV and HCV testing. Results will be disseminated to national and local policy makers to support decision making for harm reduction and health services provided to people who inject drugs.