Immunological Effectiveness of Hepatitis B Vaccination in Deviation from Vaccination Schedule in Healthy Children and Children with Chronic Diseases

Introduction. Vaccination is the primary method of preventing hepatitis B (HBV). Immunization performed according to the standard schedule often provides protective level of antibodies against HBV. However, the frequency deviation of the immunization schedule in children due to unjustified medical contraindication is the current problem in Russia. At the same time, there is currently no clear strategy for patients with significant deviations of the vaccination schedule, especially regarding extending the interval between the first and third administration of the HBV vaccine. The aim is to evaluate the immunological effects of vaccination against hepatitis B in the vaccination schedule deviation in healthy children and children with chronic diseases. Materials and methods. Eighty-one 0.7-11.7 year child with a disrupted schedule of vaccination against HBV was observed. The children were divided into two groups: children vaccinated within 12-35 months (group 1, n = 48) and children immunized more than 36 months after the first vaccination (group 2, n = 33). Children with chronic forms of pathology were included in both study groups. Blood tests for HBV antibodies after vaccination were performed 1-3 months after the third vaccination. Results. The average concentration of antibodies in the range of 10-1000 mMEd/ml in children of group 1 was significantly higher than in children of group 2 (p = 0.037). In addition, children with chronic diseases were significantly more likely to have an anti-HBs titer higher than 1000 mMEd/ml after the third vaccination than healthy children (p = 0.012). Conclusion. An increase in the interval between the first and third administration of the hepatitis B vaccine leads to a rise in the number of children who are not immune to hepatitis B. Chronic diseases fail to affect the immune response due to the introduction of the hepatitis B vaccine, even if the immunization schedule is disrupted.