Assessing the Impact of Hepatitis B Immunization among Children Aged 1-14 years in Ogbomoso, Oyo State, Nigeria

Background: Hepatitis B Virus infection is a vaccine-preventable disease. The vaccine is recommended for all children at birth within the first 24 hours of life and during childhood to prevent perinatal and early childhood HBV transmission. Nigeria introduced HBV vaccines into the National Program on Immunization in 2004 and 2007 respectively. Objective: This study aimed to assess the population impact made by hepatitis B vaccine after its integration into Nigeria’s National Program on Immunization (NPI-NIG). Materials and methods: A cross-sectional study was conducted from December, 2022 to October, 2023 in Ogbomoso, Oyo State, Nigeria. A simple random sampling technique was used to select 336 fully vaccinated children aged 1–14 years old with the presentation of their vaccination card. Blood samples were collected from each child and the plasma was used to determine status of hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc), hepatitis B envelope antigen (HBeAg), hepatitis B surface antibody titer (anti-HBs) and HIV antibody using ELISA techniques. Results: The seroprevalence of HBsAg, anti-HBc and HBeAg was found to be 4/336(1.2 %), 5/336(1.5 %) and 2/336(0.6 %) respectively. The positive cases were found among children aged 11-14 years. Of 336 fully vaccinated children, 43(12.8%) had anti-HBs titer > 10 IU/ml, while 293(87.2%) had anti-HBs titer <10IU/ml. All study participants tested negative for HIV antibody. Conclusions: Though the prevalence of HBsAg (1.2%) in the study population was lower than the national prevalence of 8.1% for the country, the low proportion (12.8%) of the vaccinated children with protective anti-HBs titer value calls for further investigations to determine if booster doses of the vaccines may be required.