Background

Our study aims were to assess hepatitis A virus (HAV) and hepatitis B virus (HBV) susceptibility and infection among young persons who inject drugs (PWID) who may have been vaccinated as children and to evaluate self-report of HAV and HBV vaccination.

Methods

We recruited PWID aged 18-40 years-old in San Diego during 2009 and 2010 and collected demographic, socioeconomic, health, and behavioral factors. Participants were asked if they had been vaccinated against HAV and HBV, and serum samples were collected for HAV and HBV serologic testing.

Results

Of 519 participants, 365 (72%) were male, 252 (49%) were white non-Hispanic, 38 (7%) were Black non-Hispanic, 138 (27%) were White Hispanic, and 22 (4%) were born outside the U. S. Of the total participants, 245 (47%) had surface hepatitis B antibody (anti-HBs) titers <10mIU/ml (i.e., HBV susceptible) and 325 (63%) had no detectable HAV antibodies (HAV susceptible). Hepatitis B surface antigen was detected in 7 (1%) of total participants; and 135 (26%) were anti-HCV-antibody positive. Compared to serologic findings, self-report of HBV and HAV vaccination was 71% and 41% sensitive, and 58% and 73% specific, respectively.

Conclusion

HAV and HBV antibodies in half or more of this young PWID population did not have levels indicative of protection, and about a quarter had HCV infection, putting them at risk for complications resulting from co-infection with HAV or HBV. Programs serving this population should vaccinate PWIDs against HAV and HBV and not rely on self-report of vaccination.

Persons who inject drugs (PWID) are at risk for adverse health outcomes as a result of their drug use, and the resulting social stigma makes this a difficult population to reach for interventions aimed at reducing morbidity and mortality. During our study of adult PWID aged ≤40 years living in San Diego during 2009 and 2010, we compared three different sampling methods: respondent-driven sampling (RDS), venue-based sampling at one syringe exchange program (SEP), and street-based outreach. We compared demographic, socioeconomic, health, and behavioral factors and tested participants for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) and compared across the three methods. Overall, 561 (74.8%) of the targeted 750 PWID were enrolled. Venue-based convenience sampling enrolled 96% (242/250) of the targeted participants, followed closely by street-based outreach with 92% (232/250) recruited. While RDS yielded the fewest recruits, producing only 35% (87/250) of the expected participants, those recruited through RDS were more likely to be female, more racially diverse, and younger.

We asked persons who inject drugs questions about HCV, including past testing and diagnosis followed by HCV testing. Of 540 participants, 145 (27%) were anti-HCV positive, but of those who were positive, only 46 (32%) knew about their infection. Asking about previous HCV testing results yielded better results than did asking about prior HCV diagnosis. Factors associated with knowing about HCV infection included older age, HIV testing, and drug treatment. Comprehensive approaches to educating and screening this population for HCV need implementation.

Data about prevalence of hepatitis E virus infection in persons who inject drugs are limited. Among 18-40-year-old persons who inject drugs in California, USA, prevalence of antibodies against hepatitis E virus was 2.7%. This prevalence was associated with age but not with homelessness, incarceration, or high-risk sexual behavior.