Serum Level of Anti-hepatitis B Surface Antigen among Newborns and Fully Vaccinated Infants and Children Aged 6 to 11 Years

Objectives: To assess the antibody level against hepatitis B surface antigen (anti-HBs) among newborns and their mothers and among recently vaccinated infants at age of 9 and 12 months. It also aimed at assessing the long-term immunity to hepatitis B among vaccinated children aged 6–11 years according to Egyptian expanded immunizing protocol. Methodology: Total no of 323 vaccinated healthy infants and children plus 45 newborns and their respective mothers were included in this study. Anti-HBs titer was assessed among 45 newborns and their mothers, recently vaccinated infants at age of 9 and12 months (30, 51) respectively and 245 children aged 6–11 years. Quantitative ELISA technique and mean anti-HBs level ± Standard Error (SE) were detected. Results: No detectable antibody level was found among newborns or their respective mothers. The mean level of anti-HBs among 30 vaccinated infants aged 9 months were 426.8 ± 71.2 IU/L and 367.4 ± 52.6 IU/l among 51 vaccinated infants aged 12 months. In a group of children (n=242) aged 6-11 years, the total mean anti-HBs level was 54.8 ± 19.5 IU/L. Among children aged 6-11 years, only 95 (39.3%) of them had protective level of anti-HBs ( 10 IU/L). The mean level of anti-HBs decreased significantly with increasing age (P = 0.026). A significant negative correlation was found between current age and antiHBs levels (P < 0.0005). No significant difference was detected between males and females or among different level of socioeconomic status (P>0.05). Conclusion:. More than half of the studied children had non-protective level of anti-HBs and this puts them at risk of infection. The failure to achieve satisfactory seroprotection level by the national immunization programme reflects the need to reevaluate the current hepatitis B vaccination strategy in Egypt.