letters were mailed to 140 patients recommending HIV, hepatitis B, and hepatitis C testing. After receiving the notification letter, patient D contacted the clinic. He was hospitalized for hepatitis C in a different county during August 2022. Patient D received a procedure on the same day, in July, as the other 3 patients and immediately after patient B. To encourage testing and to ensure receipt of exposure notification letters, we called all 140 patients; 100 (71%) were successfully contacted and 76 (54%) reported they had scheduled or completed recommended postexposure testing. Recommendations to the clinic included updated infection control practices, proper use of syringes and needles, keeping multidose vials in a dedicated clean medication preparation area (away from immediate patient treatment areas), staff training, and an outbreak notification sign for the clinic to post. 8 We continued cross referencing the exposure patient list with the California Department of Public Health and LACDPH HCV registries. No additional patients with a positive HCV RNA test result were reported.Although we were unable to identify a specific source of HCV transmission, evidence supports the possibility that a multidose medication vial was contaminated by reuse of a needle or syringe. Improper handling of multidose vials has been linked to multiple bloodborne pathogen outbreaks 2,3 and are the basis of CDC recommendations for safe injection practices when using multidose vials. 9 Single-use vials, drawing medication outside the patient's room, and random audits of infection control practices by infection prevention staff or departments of public health could prevent future outbreaks. 9 Our investigation highlights an ongoing need to assure that providers consistently apply policies and procedures to prevent healthcare-associated transmission of bloodborne pathogens when using multidose vials.