ABSTRACT
This study was carried out to determine the serum concentrations of anti-hepatitis B virus antibody [Anti-HBs] in 1-4 years old being vaccinated against hepatitis B. By drawing 2ml of venous blood from 175 children admitted for unrelated reasons to Yazd central medical laboratory and using a 3rd -generation ELISA test, the serum level of anti-HBs was quantitated. A questionnaire was used for obtaining data about age, sex, birth weight, current weight, schedule of previous hepatitis B vaccination, history of pathologic neonatal jaundice, and any serious health problem during childhood. In 170 of the cases [97.1%] the Anti-HBs concentration was above 10m IU/mL, routinely regarded as protective. No significant difference was observed concerning the various ages of subjects and their sexes, but anti-HBs levels were meaningfully lower in low-birth weight neonates [P-value<0.01], in children with history of pathologic neonatal jaundice [P-value =0.002] and in those having a previous serious disease [P-value=0.006]. The overall efficacy of vaccine is good, but in children who had had low-birth weight, pathologic neonatal jaundice, or any serious disease, careful follow-up must be carried out to ensure that protective levels of Anti-HBs are achieved after vaccination