Seroconversion of Hepatitis B Vaccine in Young Bangladeshi Children: A Tertiary Centre Experience

Background: Hepatitis B virus (HBV) infection is one of the most important global health problems and active immunization is the single most important and effective preventive measure against HBV infection. Several studied show that HBV carrier rate is between 2% - 7% in Bangladesh. Bangladesh introduced hepatitis B vaccination in children through Expanded Program on Immunization (EPI) in 2005 that includes 3 doses which starts from six weeks after birth. Currently booster vaccination is not recommended any more. However, many studies on different countries observed a declined level of HBs-antibody over a period of 3 - 6 years that may even reach to non-protective levels. Objective: To evaluate the status of seroconversion and seroprotection along with non-responders of EPI vaccinated children against HBV and to measure their antibody levels in different age groups. Methods: A cross sectional descriptive study was done in the department of Pediatric Gastroenterology, Hepatology & Nutrition, Dhaka Shishu (Children) Hospital, Dhaka, Bangladesh on 120 cases of EPI vaccinated children enrolled from January-December 2019 while attending the inpatient department without any liver problem. The development of Anti-HBs titre greater than or equal to 10 mIU/mL is considered as protective immunity and any titre less than 10 mIU/mL as non-protective following HBV vaccination. Results: Age of the children was 1 - 12 years with mean age of 5.6 ± 1.7 years and male: female ratio was 1.1:1. Among the children, 56 (46.6%) were from 1 - 5 years age, 36 (30.1%) children from 6 - 10 years age group and 27 (23.3%) children from 11 - 12 years age group. Out of 120 children, presence of Anti-HBs protective titre was in 63 (52.5%) children and non-protective level in 57 (47.5%) children. Among protective level, 34 (60.7%) children were in 1 - 5 years age group, 18 (50.0%) children in 6 - 10 years age group and 11 (39.3%) children in 11 - 12 years age group. Total 24 (20%) children were completely non-responder (antibody titre 0.00 mIU/mL). Out of 120 mother, 06 (5%) were HBV positive. Among them 05 (83.33%) children had Anti-HBs less than 10 mIU/mL. Conclusion: After primary vaccination, a good immune response was detected against hepatitis B virus but it goes below even up to non-protective level with the increase of age. Half of the studied children had non-protective titre after 5 years and one-fifth children totally non-responder after primary hepatitis B vaccination. A booster dose may be recommended after 5 years for optimum seroprotection.