Hepatitis B Virus Vaccine immune response in Egyptian children 15-17 years after primary immunization; should we provide a booster dose?

Background: Few studies have evaluated the seroprotection of HBV vaccines among healthy Egyptian children after receiving the primary immunization. Yet, up to our knowledge none of them has evaluated the immune status to HBV vaccine among Egyptian children older than 15 years. Objective: To assess the seroprotection as well as immunological memory against HB virus more than 15 years after receiving the primary set of vaccination. Methods: Serum anti-HB surface antibody was measured in 225 healthy adolescents. Their ages ranged from 16-18 year with a definite history of receiving the primary immunization for HBV at infancy. A booster dose of the HB vaccine was given to 56 of the candidates in whom serum level of anti-HB surface antibody was not protective (less than 10 mIU/ml). A second evaluation of anti-HBs was done in those 56 one month after the booster dose. Results: Only 8.9% of our cohort have a protective anti-HBs antibody when measured 15-17 years after primary vaccination set. On the other hand, 100% of the 56 children who received the booster dose showed excellent anamnestic response. Conclusion: Despite the loss of protective levels of anti-HBs antibody among healthy low risk adolescents 15-17 years after primary HB immunization set, strong anamnestic response indicates the presence of good immunological memory.