Relationship Between Age and Response to Immunization of Family Members of Chronic Hepatitis B Patients

Objective: First-degree relatives of patients with histological and serological diagnosis of chronic hepatitis B should be immunized; however, the response to immunization varies according to age. In this study, we evaluated the response to immunization in siblings of chronic hepatitis B patients. Material and Methods: HbsAg(-) family members of 100 index patients with chronic hepatitis B virus (HBV) were immunized with HBV vaccine at 0, 1, and 6 months, and were divided into three groups according to their ages, as follows: group 1, 0-10 years old; group 2, 11-20 years; and group 3, >20 years. After each vaccination, the responses to immunization, determined by anti-HBs positivity, were compared between the three age groups and were evaluated by the SPSS 12 computer program. Results: The study group comprised 205 cases 1-60 years old (mean 20.26 +/- 12.18). The antibody responses at month 0, 1, and 6 were 4.3%, 66.7%, and 100% in group 1; 3.4%, 31.5%, and 85.6% in group 2; and 1.4%, 38.2%, and 74.6% in group 3, respectively. According to the Mantel-Haenszel chi-square test, the immune response of patients below 20 years of age was significantly higher than the response of those above 20 (Mantel-Haenszel chi-square= 14.54, p< 0.00013). Conclusion: Immunization in the first decade of life is important to prevent the spread of HBV infection. First-degree relatives of chronic HBV patients must be vaccinated and the immune response must be checked.