Impact of routine infant and adolescent hepatitis B vaccination in Tuscany, Central Italy

Background. In Italy routine infant and adolescent immunization against hepatitis B was introduced in 1991. Objective. Evaluation of (1) coverage with three doses of hepatitis B vaccine in infants and adolescents; (2) seroconversion to anti-hepatitis B surface antigen antibody (anti-HBs) in adolescents receiving three doses of vaccine; (3) concordance of coverage rates in infants with prevalence of neutralizing antibodies in sera from anonymous children; (4) trend of notified cases of acute hepatitis B. Methods. A sample of infants and adolescents living in Tuscany was studied during 6 years (1992 through 1997) by matching birth records and immunization certificates. Sera from 139 adolescents who completed the vaccination course and from 159 anonymous children belonging to immunized cohorts (1 to 5 years) were tested with a quantitative anti-HBs assay. Incidence of acute hepatitis B by age was calculated from regional statistics on notified infectious diseases between 1992 and 1996. Results. Overall 10 606/11 164 (95%) infants and 10 599/11 100 (95%) adolescents received 3 doses of vaccine. Seroconversion to anti-HBs was detected in 98% of adolescent vaccinees. Anti-HBs titers greater than or equal to 10 IU/I were detected in 87% of children. A 49% decline of acute hepatitis B cases was registered between 1992 and 1996 in 15- to 24-year-olds living in Tuscany. No case occurred in vaccinated adolescents. Conclusions. Coverage against hepatitis B is excellent in cohorts subject to mandatory immunization. If efforts to vaccinate are maintained at these levels, elimination of hepatitis B virus transmission could occur within few decades in Italy.