Hepatitis B Vaccination in Children with Thalassemia, Hemophilia and Cancer

Abstract

To The Editors: Hepatitis B virus (HBV) infection is endemic in Turkey as well as other Mediterranean countries, with a high frequency in children. It results in cirrhosis, hepatocellular carcinoma and death.1-3 In hematologic disorders such as thalassemia, hemophilia and cancer, it is most likely related to multiple blood transfusions and hospital contacts. Also cytotoxic therapy may alter the immune response of patients to HBV infection.4-6 HBV vaccines have been largely shown to be effective in preventing infection of healthy children and young adults with an efficacy of >90%.7, 8 Turkey does not have a national policy about routine infant immunization with HBV vaccine because of the high cost. However, in contrast to excellent induction of protective antibodies in healthy children, the results in hemodialysis and immunocompromised patients such as those with cancer have been disappointing.8 In this study our purpose was to investigate the success rate of immune response to HBV vaccine for children with hematologic malignancies (n = 70), transfusion-dependent beta-thalassemia (n = 26), hemophilia (n = 20) and other hematologic disorders such as iron deficiency anemia and immune thrombocytopenic purpura (n = 26). A total of 142 children followed up in Ege University Hospital entered the study between 1991 and 1995. The characteristics of the patient groups are given in Table 1. Thirty-six cancer patients had lymphoproliferative tumors such as leukemia and lymphoma and 34 had solid tumors. All patients were serologically negative for hepatitis B surface antigen, anti-hepatitis B surface and anti-hepatitis B core. Recombinant HBV vaccine (GenHevac B®; Pasteur-Merieux, Lyon, France) was administered intramuscularly initially and at 1 and 2 months later at a dosage of 20 μg; however, a double dose (40 μg) was used in cancer patients in an attempt to increase the success rate. The viral serologic analyses were performed by micro-enzyme immunoassay methods (Organon Teknika, Boxtel, The Netherlands). Response to vaccine was considered to be anti-hepatitis B surface titers that reached protective values (>10 mIU/ml) in the fourth month of the serologic control In nonresponder cases we continued the second and third course of vaccination with monthly intervals until seroconversion was achieved to protective titers. In the fourth month check-up the seroconversion rate was obtained with a ratio of 60% for cancer, 73% for thalassemics, 95% for hemophiliacs and 92% for the other patients. We have shown that more injection and/or high doses of vaccine may improve immune response.7 With booster doses, at the end of the first year the seroconversion rate reached 85% in patients with cancer and 92% in thalassemics. This success rate was similar to that of healthy children (≈80 to 95%) and is the highest rate in the cancer population to our knowledge.7, 8 In conclusion encouraging results may be obtained in hematologic disorders including immunocompromised cancer patients. Repeated courses with double doses should be administered in those patients until seroconversion is achieved. Kaan Kavakli, M.D.; Gungor Nişli, M.D.; Nazan Çetingül, M.D.; Senay Öztop, M.D.; Altinay Bilgiç, M.D.; Tijen Özacar, M.D. Departments of Pediatric Hematology (KK, GN), Pediatric Oncology (NÇ, SÖ) and Clinical Microbiology (AB, TÖ), Ege University, Faculty of Medicine Bornova, Turkey