Immunity against hepatitis B in a selected child population in Gampaha district, Sri Lanka, ten years after vaccination at two, four and six months of age

Abstract

Background: Hepatitis B (HB) infections are a global public health concern, which carry high morbidity and mortality. Immunization is the safe and effective intervention to prevent transmission. Currently, the Hepatitis B vaccine is given to children at two, four and six months of age in Sri Lanka. However, the capability of this regimen in providing long term protection up to adolescence and beyond remains a concern. The current study was conducted to assess the HB immune status of children, ten years after vaccination during infancy. Methods: Antibody status of 150 children who received HB vaccine at two, four and six months of age was assessed 10 years after the last dose of vaccination. Some of these children had received liquid monovalent HB vaccine, while others were vaccinated with the Hexavalent vaccine. Children with HB antibody levels below the protective level were given a booster dose of monovalent recombinant HB vaccine, and antibody levels were reassessed in one month. Results: At the initial assessment, 128 children (85%) had protective levels of antibodies. Type of vaccine and gender had no significant effect on the prevalence of HB antibody levels (p>0.05). All children who received the booster dose developed protective levels of antibodies. Conclusions: Most of the children immunized against HB during infancy maintain protective antibody levels at 10 years of age. Children with antibody levels below protective levels produced a rapid anamnestic response following a booster dose..

Keywords

• hepatitis b, immunity, immunization, antibodies