Breakthrough hepatitis B virus infection and its associated factors among vaccinated children in Northwest Ethiopia

Despite the availability of an effective vaccine, the global prevalence of chronic hepatitis B (CHB) in children was estimated to range from 1.3 to 3.4%. In Ethiopia, the estimated seroprevalence of CHB in children under five years old was 2.21%. This study aimed to assess the prevalence of breakthrough hepatitis B virus (HBV) infection and its associated factors in northwest Ethiopia. A cross-sectional study was conducted in northwest Ethiopia from December 2023 to June 2024. Children aged 1-14 years who visited pediatric clinics for various medical reasons were enrolled. Hepatitis B surface antigen (HBsAg) was tested using an enzyme-linked immunosorbent assay (ELISA). Data were analyzed using SPSS version 23.0. Chi-square tests and logistic regression analyses were employed to identify predictors of breakthrough HBV infection, with statistical significance set at p < 0.05. Among 325 vaccinated children under 15 years of age, the prevalence of breakthrough HBV infection was 2.5% (95% CI: 0.9-4.3%). The age of the children and a history of contact with individuals with CHB were significantly associated with breakthrough infection. Children aged 5-9 years were 10.7 times (OR = 10.7; 95% CI: 1.1-99.6), and those aged 10-14 years were 20.7 times more likely to be infected with HBV (OR = 20.7; 95% CI: 2.0-215.8), compared to children aged 1-4 years. Additionally, children with a history of contact with CHB individuals were six times more likely to be infected with HBV (OR = 6.1; 95% CI: 1.4-27.6). This study found an intermediate prevalence of HBV infection among vaccinated children, which raises significant public health concerns. Age and contact with individuals with CHB were found to be significant factors associated with breakthrough HBV infection. These findings highlight the need for regular evaluation of the effectiveness of vaccination programs and the implementation of targeted preventive strategies to reduce transmission.