An evaluation of the efficacy of the national immunization programme for hepatitis B.

We report an evaluation of the Israeli national immunization programme for hepatitis B in the Haifa subdistrict. We used a convenience sample of blood tests reported positive for HBsAg over a 6-year period from children who were born after routine immunization began in 1992. We identified 11 children with presumed chronic hepatitis B virus infection who were residents of the Haifa subdistrict, three of whom were born in Israel. All three were immunized at the appropriate age and are thus considered vaccination failures rather than failure to vaccinate. The remaining eight were born abroad, had emigrated to Israel as children and were not immunized at birth. We estimate the rate of chronic hepatitis B virus infection for children born since 1998 to be 0.24/10,000 births. For all children resident in the subdistrict under the age of 12 years, the period prevalence is estimated to be 1.26/10,000. The rate of chronic infection in children younger than 12 years was significantly less than that of older cohorts and less than that of historical controls before the start of immunization. Although the reported rates are probable underestimates of actual rates, the fact that they are based on testing carried out in clinical settings increases the likelihood of positive findings and thus reduces the degree of error. The fact that most young carriers are foreign born points to the importance of timely catch-up programmes. In countries with low and intermediate rates of chronic infection, serosurveys of immunized children need to be large and are therefore costly. Monitoring HBsAg positive tests from routine testing carried out in clinical settings is an inexpensive way to monitor chronic infection rates.