Hepatitis B Virus Immunization Among Young Injection Drug Users in San Francisco, Calif: The UFO Study

Hepatitis B virus (HBV) infection is common (44%–80%) in injection drug users (IDUs),1–8 and younger IDUs are at high risk.9–11 Although a safe and effective vaccine is available, high vaccine completion rates in IDUs (70%–86%) have been achieved primarily in drug treatment settings.12–15 Among street-recruited young injectors in San Francisco, Calif, only 13% had serological evidence of prior immunization, and 28% had been infected with HBV.16 We combined cash incentives and street outreach with flexible immunization schedules to improve HBV vaccine completion in young injectors in San Francisco. We examined factors associated with vaccine completion and observed postvaccination antibody responses in completers.