Seroprevalence of hepatitis B in two period birth cohorts of Bolivian children: effect of universal vaccination.

Background: Since 2000 universal routine immunization against the hepatitis B virus (HBV) was implemented in Bolivia. This study aimed to assess the seroprevalence of markers against HBV in two different birth cohorts (pre-universal vaccine cohort and post-universal vaccine cohort) from Cochabamba, Bolivia.

Methods: We performed a school-based seroepidemiological survey (n = 424) of HBV in 2010 in the Cochabamba region. An ELISA test was used to measure antibodies to the hepatitis B surface antigen (anti-HBs IgG) and to the hepatitis B core antigen (anti-HBc IgG).

Results: The prevalence of anti-HBs IgG in the pre-universal vaccine cohort was 5.8% (95% CI: 3.3-8.3%); it was higher in boys (9.1%), and those living in suburbs (9.7%). The anti-HBs IgG prevalence among post-universal vaccine cohort was 37.9% (95% CI: 28.5-48.1%), and was higher in children who spoke Quechua at home (51.0%), those living in suburbs (53.9%), and those born in 2005 (72.7%). Neither cohort showed differences relating to parental education. The prevalence of anti-HBc IgG was 1.1% among post-universal vaccine cohort and 1.2% among pre-universal vaccine cohort (p > 0.05).

Conclusions: This study identified a persistent low seroprevalence of hepatitis B infection in spite of a decade of universal immunization, and low long-term humoral immunity against HBV infection in vaccinated children in Cochabamba.