ده سال پس از واكسيناسيون همگاني در دوران نوزادي B دوام و خاطره ايمني واكسن هپاتيت

To evaluate the long-term immunity and immunologic memory provided by universal hepatitis B vaccination program at birth, and to evaluate the booster effects of different dosages of hepatitis B vaccine on children, who lost protective antibody titers to hepatitis B surface antigen (HBs -Ag), this study was conducted. Methods: community-based sero-epidemiologic study was done on 453 healthy 10.5 years old Iranian children, one decade after implementation of a mass hepatitis B vaccination program. A booster vaccination with different dosages was given for children who did not have protective level of anti-hepatitis B surface antigen antibody (anti-HBs). Quantitative serologic responses to different dosages of vaccine were compared using X2 statistical test. Results: A total of 42% children (191 of 453) children had low concentration (<10IU/L) of anti HBs antibody, 18.5% (84 of 453) were susceptible (antibody titer <2IU/L). 87.2% of 165 nonprotected-boostered vaccines showed immunologic memory to different doses of booster, and developed protective antibody titer two weeks later. The differences between pre- (3.48 ± 3.39; mean ± SD) and post- (153 ± 163.84) vaccination antibody titers were significant (p=0.000). Antibody titers achieved by different doses of vaccine had significant proportion to vaccine doses. No hepatitis B infection markers were detected in those children who were not sero-protected and did not respond to booster dose of vaccination. Conclusion: According to these findings, universal hepatitis B vaccination program at birth provides adequate protection against hepatitis B virus infection at least for 10 years. It might suggest that booster vaccination is not recommended, but further follow-up studies at adulthood age group are recommended.