Serum Level of Antibody to Hepatitis B Surface Antigen and Associated Factors among Vaccinated and Unvaccinated Children in Harar town, Eastern Ethiopia: A Community Based Study

Abstract

Background: Hepatitis B virus infection is a major world health problem which is known to be the main cause of liver failure, cirrhosis, and hepato cellular carcinoma. Production of antiHepatitis B surface which is stimulated by Hepatitis B Virus vaccine causes protection of antibody against clinical infection. However, not all vaccinated individuals develop protective level of antibody against Hepatitis B surface Antigen. Objective: The main objective of this study was to assess serum level of antibody to hepatitis B surface antigen among vaccinated and unvaccinated children in Harar town, Eastern Ethiopia. Method: Community based Comparative cross sectional study design was conducted among 475 vaccinated and 475 unvaccinated children in Harar town, Eastern Ethiopia. Whole blood sample (3-5ml) was collected from the study participants who were selected by simple random sampling from the list of 5-8 years old children in selected kebeles and Enzyme Linked Immuno-sorbent assay machine was used for detection of total antibodies to Hepatitis B surface antigen in plasma of collected sample. Pre-tested, structured questionnaire was used for gathering information about socio demographic characteristics of the study participants and factors associated with level of antibody. Epi-data version 3.02 was used for data entry. Data was analyzed using statistical package for social sciences software version 20. Logistic regressions with 95% CI were used to identify independent predictors of anti-HBs. P-value of less than 0.05 was taken as level of significance. Results: The overall sero-protection rate detected in this study was 96.5% among vaccinated children. However, 7.3% of unvaccinated children had anti-HBs level >10mIU/mL. Protective antibody levels were detected in 47.2% of vaccinated children five years after vaccination and it was then decreased to 26.5%, 17.4%, and 5.4% after 6, 7 and 8 years of initial vaccination respectively. Current age of the child, doses of vaccine and vaccination status were independent predictors of anti-HBs levels. Conclusion and Recommendation: protective amount of anti-HBs were detected in 96.5% of vaccinated children and vaccination of children in infancy produces adequate protection 5 to 8 years post vaccination. However at least unvaccinated children who were born after HBV vaccine commenced should have to be vaccinated for proper protection from HBV infection.