Low prevalence, low immunization and low adherence to full hepatitis B vaccine scheme and high-risk behaviors among crack cocaine users in central Brazil.

Crack cocaine users represent a target group for hepatitis B vaccination. We evaluate the HBV epidemiology, immunization status and compliance with a super-accelerated vaccination schedule among in-treatment crack cocaine users in central Brazil. Six hundred in-treatment crack cocaine users were interviewed, and serum samples were tested for HBV markers. A super-accelerated vaccination schedule of HBV vaccine was offered to all susceptible crack cocaine users. In total, 7.0% of those tested had at least one positive marker of HBV exposure. Age, use of crack cocaine through improvised pipe, exchange of sex for money/drugs and previous sexually transmitted infections (STIs) were predictors of HBV exposure. One hundred six (17.7%) individuals showed a serological profile of hepatitis B vaccination. Of these, 54.7% were less than 25 years old, and only 13% of individuals were more than 35 years old. Although 91.8% of crack users accepted the first vaccine dose, only 21.7% received all three doses. Of the 23 crack cocaine users who agreed to have their vaccine response evaluated, 78.3% developed protective anti-HBs titers. Premature termination of treatment was the most common reason for not receiving the full vaccine series. Despite the low prevalence of HBV exposure among in-treatment crack cocaine users in central Brazil, the low rate of immunization and the high frequency of high-risk behaviors highlight the potential for crack users to acquire and disseminate this infection and therefore maintain the viral reservoir. Health practitioners need to keep this in mind, taking advantage of all opportunities to access this population and vaccinate against HBV.