Injection drug users are at increased risk for hepatitis B. Surveillance of the unexposed to infection and of the vaccinated is necessary to understand the impact of interventions. We aimed to analyze HBV serum profiles and rates of HBV vaccination over 20 years.
Methods: Cross-sectional study in IDUs admitted to detoxification between 1987 and 2006 in two hospitals in Barcelona, Spain. Clinical data and serum samples for HBV, HCV and HIV infections were collected. HBV serostatus was assessed with HBsAg, Anti-HBs and Anti-HBc.
Results: A total of 1223 IDUs were eligible; 80.3% were men; median age at admission was 28 years. Prevalence of HCV infection and HIV infection was 84.2% and 44.3%, respectively. There was a significant (p<0.001) increase of the rates of HBV vaccine-induced immunity from 3.7% in period 1987-1991 to 19.9% in period 2002-2006 and, a significant (p<0.001) decline of those with HBsAg from 9.3% in 1987-1991 to <2% after 1997. The rates of absence of HBV markers and of natural immunity remained stable from 1992 onwards. In multivariate logistic regression model, HBV vaccination was significantly (p<0.001) less frequent in older individuals (OR=0.61 [95% CI: 0.50-0.74] for a 5-year increase in age) and in HIV infected patients (p=0.014) (OR=0.51 [95% CI: 0.30-0.87]).
Conclusions: In the 20-year period from 1987 to 2006, HBV vaccine-induced immunity in IDUs has shown an upward trend, although overall prevalence remained low. More effective interventions are needed to reduce high rates of HBV infection in this population.
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