RESUMEN
<p><b>OBJECTIVE</b>To evaluate the long-term protective effects of hepatitis B vaccine after immunizing to the children for 12 years in Beijing.</p><p><b>METHODS</b>The multiple stratified cluster sampling was used in this epidemiological survey. The sampling children's blood serum HBsAg, anti-HBs and anti-HBc were checked and measured by the solid phase radioimmunoassay (SPRIA). The serological level of these index and the causes of the children with HBsAg positive were analyzed.</p><p><b>RESULTS</b>There were 2,419 cases 3-12 years-old children immunized with the hepatitis B vaccine in infant period were surveyed and the total HBsAg positive rate was 0.52%. The vaccine protective rate was 88.45% (95% CI: 65.67%-97.89%). The total anti-HBc positive rate was 2.21%, being no statistical significance among the age groups. The average anti-HBs positive rate of 3-6 years-old children immunized with gene recombining vaccine was 38.79% and descending greatly following the age's dropping. The geometric means of anti-HBs serological titer (GMT) was 52.83 mIU/ml, showing no statistical significance among the age groups. The average anti-HBs positive rate of 6-12 years-old children immunized with the blood rooting vaccine was 50.79%. The geometric means of anti-HBs serological titer (GMT) was 61.51 mIU/ml. There were no statistical significances among the age groups. Among the HBsAg positive children, more than 50% of the children's mothers were HBsAg positive also.</p><p><b>CONCLUSIONS</b>The protective effects given by immunization were significant after the hepatitis B vaccine vaccination for 12 years in Beijing. The booster immunization was not necessary, because the HBsAg positive rate didn't ascend obviously as the immunization time prolonging. As the anti-HBs positive rate of children who were immunized by the gene recombining vaccine might be descending following the age's dropping greatly, we should strengthen the serological surveillance of hepatitis B. The main cause that the children became the HBsAg carrier should be a vertical transmission.</p>