Immune protection of hepatitis B vaccine among children living in Gondar, northwest Ethiopia

Background: Hepatitis B virus infection is a worldwide health problem and highly endemic in developing countries including Ethiopia. Hepatitis B vaccine is included in the routine Expanded Program on Immunization since 2007 in Ethiopia. Objective: The aim of this study is to assess the seroprotection level of hepatitis B vaccination among children who have received the vaccine. Methods: A cross-sectional study was conducted on children attending kindergarten and elementary school in Gondar. A pretested structured questionnaire was used to collect the sociodemographic data. Blood samples were collected and serum separated to measure anti-HBs, anti-HBc, and HBsAg levels. Data were analyzed using SPSS statistical software version 21. Binary logistic regression analysis was done. P-value less than 0.05 was considered as statistically significant. Results: Out of 431 children screened, 27 were excluded from analysis because they were positive for anti-HBc (27/431, 6.3%) and/or for HBsAg (18/431 or 4.2%). Out of the rest 404 children, 130 (32.2%) had anti-HBs titers >10 mlU/ml (seroprotected), while 274 (68.8%) had anti-HBs titers 100 mlU/ml). In multivariate analysis, children of age 6 and 8 years old were 2.4 times (AOR: 2.436, 95% CI 1.049-5.654) (P=0.038) and 3.3 times (AOR: 3.397, 95% CII.306-8.837) (p=0.012) better responders compared to 9 years old children, respectively. Moreover, children whose mothers had no previous history of hepatitis were 2.0 times (AOR: 2.009, 95% CI 1.101-3.665) (P= 0.023) better responders compared to their counterparts. Conclusion: The seroprotection level among vaccinated children in Gondar was surprisingly low. Age and children from mothers with a history of hepatitis B infection were associated with seroprotection. The preliminary findings obtained in this study call for a thorough assessment of the effectiveness of the current hepatitis B vaccination program in this study region