Immune Status of Cohort of Children Vaccinated against Hepatitis B Virus in Ekiti State over Ten Years after Incorporation into National Program on Immunization

Background: Hepatitis B vaccine has been introduced in Nigeria for over a decade now, yet, data on sero-conversion status of the immunized cohort in the population are scarce. Such data are important for objective evaluation of the impact and effectiveness of the HBV vaccination program. This study therefore aims at determining the sero-conversion status and the prevalence of HBV infection among immunized cohort of children in Ekiti state, Nigeria.

Methodology: This cross-sectional study was conducted across the three senatorial districts of Ekiti state, between October and December, 2017. A total of 441 children consisting of 226 males and 215 females (Male to female ratio= 1.1:1). Immunization was confirmed by immunization cards. Multistage sampling technique was used. Questionaire were administered after caregiver’s consent and assent from subjects, 2 to 5 mls of blood samples were then collected and tested for the various hepatitis B viral markers (HBeAg, HBeAb, HBcAb, HBsAb and HBsAg) using Hepatitis B combo kit manufactured by Innovita Biological Technology. Very low levels antibody titres which may not be detectable by qualitative detection method used is a limitation to this study.

Results: Subjects were between 5 to 10 years. All subjects had 3 full doses of hepatitis B vaccination before the age of 1 year and all subjects were negative for HBsAg, HBeAg, HBeAB and HBcAb. However, only 47 (10.7%) had detectable HBsAb. Among HBsAb positive patients 22 were males while 25 were females. Our findings showed zero prevalence of hepatitis B but minimal seroconversion rate among vaccinated children in Ekiti state, Nigeria.

Conclusion: Hepatitis B vaccination protects children against HBV in the study population. However, seroconversion rate showed that majority of the children may be at risk of HBV infection at a later age. We recommend a booster dose of HBV vaccination.