Declining prevalence of hepatitis B virus infection in Catalonia (Spain) 12 years after the introduction of universal vaccination

AIMS: To analyze the prevalence of hepatitis B virus infection markers and hepatitis B vaccination in a representative sample of the juvenile and adult population of Catalonia and to evaluate the changes with respect to seroepidemiological surveys carried out in 1989 and 1996. DESIGN: In all subjects anti-HBc and anti-HBs antibodies and HBsAg were determined using an ELISA test. The possible association between sociodemographic variables and the prevalence of markers was analysed by calculating the adjusted odd ratio (simple logistic regression). SETTING: The study was carried out in 2002 in representative samples of the juvenile (5-14 years) and adult population (>or= 15 years) of Catalonia (Spain). MAIN RESULTS: In 2002 the global prevalence of HBsAg+ was 0.7% (95% CI: 0.4-1.0) and that of anti-HBc+ 8.7% (95% CI: 7.6-9.8), values higher than those obtained in 1989 of 1.5% (95% CI: 1.0-2.1) and 15.6 (95% CI: 13.9-17.3). The prevalence of markers of infection increased with age. The only sociodemographic variable significantly associated with the prevalence of hepatitis B virus infection was the place of birth. The risk of infection was twice as high in subjects born outside Catalonia (p<0.01), adjusted OR 2.0 (95% CI: 1.34-2.98) compared with those born in Catalonia. CONCLUSIONS: The results of this study show that the prevalence of hepatitis B virus infection (anti-HBc+) in Catalonia (Spain) is currently the lowest it has ever been and suggest that there has been a change in the pattern of endemicity of hepatitis B virus infection in Catalonia, which has become a country of low endemicity.