Title : Immune response to Hepatitis B vaccination among children under 5 in a highly endemic country in Sub-Saharan Africa; Uganda
Background: Hepatitis B virus vaccination plays a crucial role in preventing Hepatitis B infection, particularly in high-risk groups such as children under-five, who have a 60-90% higher chance of seroconversion. As per the World Health Organization (WHO), about 5–10% of infants may not respond effectively to the vaccination, leaving them vulnerable to Hepatitis B virus and its complications. The paucity of data on the Immune response to hepatitis B Virus vaccination among children raises the question of how protected our children in Uganda are against Hepatitis B.
Objective: To determine the immune response to Hepatitis B vaccination and associated factors among children under five attending the outpatient care at Mulago Assessment Centre Pediatrics clinic.
Methods: This was a cross-sectional study among children (1 to < 5) years attending MAC Paediatrics clinic at Mulago National Referral Hospital who met the eligibility criteria in the month of February, 2023. All children 1-5 whose caregivers gave consent were enrolled and a pretested study questionnaire was administered by trained research assistants. Blood samples taken for analysis; Hepatitis B core antibody screening and anti HBs Ag titres by Electrochemiluminescence using the Cobas 6000. Descriptive analysis using proportions was used to determine the immune response as good or Poor response. Logistic regression analysis was done to determine factors that were independently associated with the different categories of immune response.
Results: Total of 301 children under 5 years, majority aged 2 years (29.6%). All were negative for the Hepatitis B core antibody. The immune response from 2 IU/ml to 1000 IU/ml with median titres of 86.2 IU/ml (IQR: 14.5, 239.4). 77.4% (233/301) (95% CI: 72.3% - 81.8%) had a good response and 58.4% (136/233) (95% CI: 51.9% - 64.6%) very good responders. Younger age and caregiver HIV status being negative were found to be independently associated with a good immune response.
Conclusion: Children at MAC Paediatrics clinic had a protective level of antibodies to HBV vaccine at 77% which is still less than the expected 95% by WHO. Younger age and negative parental HIV status were independently associated with good response. Emphasis should be made on birth dose, booster to at risk groups and periodic studies to monitor the response in children.