Immunogenicity of Recombinant Hepatitis B Vaccine Among Routinely Vaccinated Healthy and Chronically Ill Children in Assiut, Upper Egypt

Egypt is considered a region of the intermediate prevalence of hepatitis B virus (HBV) infection (4.5%). Seroprotection is assured when hepatitis B surface antibody (HBsAb) levels are ≥ 10 mIU/mL. Our study aimed to evaluate and compare the long-term immunogenicity and efficacy of the recombinant hepatitis B (HB) vaccine. A cross-sectional study was done for children aged from 9 months to 15 years, receiving health care at Assiut University Children's Hospital, Assiut, Egypt in 3 months. HBsAb was quantitatively determined by enzyme-linked immune sorbent assay (ELISA). Seroprotection in infants less than 1 year was 89.7% with 55.2% having titer > 100 mIU/mL and this percent dropped to 64.4% after the first year of age with only 29% having titer > 100 mIU/mL. The overall protection percentage was 32.5% (> 100 mIU/mL), 34.7% of children showed levels between 10 and 100 mIU/mL, while 32.8% were less than 10 mIU/mL. Patients with diabetes mellitus were found to have the lowest seroprotective levels (83.3% were not protected). Non-protective levels were also detected in patients with malnutrition (55.6%), congenital heart diseases (43.2%) and chronic liver diseases (57.1%). Our study shows failure to achieve satisfactory seroprotective levels for hepatitis B vaccine in both healthy and diseased children who adopted vaccination schedule in Upper Egypt. Booster dose in the second year of life is recommended for all children, particularly for those with diabetes millets, congenital heart disease and malnutrition.