Vaccination barriers and opportunities at syringe services programs in the United States, June–August 2021—A cross-sectional survey

•This cross-sectional survey of 105 U.S. syringe services programs (SSPs) examines barriers to vaccination services.•Increasing vaccinations at SSPs will require a comprehensive approach to increasing staffing, training, and resources.•More staff authorized to administer vaccines are needed to increase vaccination services at SSPs.•Large SSPs operated by urban, community-based organizations need the greatest support to increase vaccination services.