Hepatitis B mass immunization of adolescents: a pilot study in a community.

The National Type Specific Hepatitis Surveillance System (SEIEVA) and seroepidemiological studies have shown that in addition to newborns from mothers who are carriers for hepatitis B surface antigen (HBsAg), adolescents are at high risk of acquiring type B hepatitis virus because of increasing importance of the heterosexual transmission of this virus. In order to evaluate logistic problems and acceptance rate of adolescents to mass vaccination against hepatitis B, a pilot study was carried out among all 7th grade children registered in the 9 schools of an hepatitis B endemic area located in the suburbs of Naples. After meetings held by the local health department with school teachers and parents, 1219 out of 1250 (97.5%) invited children received the first dose of hepatitis B vaccine; 1215 and 1209 received, respectively, the second and third doses. Anti-hepatitis B surface antigen (anti-HBs) values were studied in 406 subjects one month after the third dose, and 21 out of 406 (5.2%) had anti-HBs values less than 10 IU/L. We consider 95% of subjects with anti-HBs values greater than 9 IU/L a good achievement for a field vaccination program. The high acceptance rate of vaccination found in our study outlines the importance of active offer of vaccination combined with school involvement.