Immunisation after hepatitis B polyvalent vaccination among children in South Kivu Province, Democratic Republic of the Congo

Background. The World Health Organization recommends the integration of vaccination against hepatitis B virus (HBV) into the national immunisation programmes of all highly endemic countries. Protective efficacy, defined as a hepatitis B surface antibody (HBsAb) level ≥ 10 mIU/mL, is ideally obtained in >90 - 95% of immunised children. The Democratic Republic of the Congo (DRC) implemented this recommendation in 2007 by introducing administration of hepatitis B vaccine in a combined formulation. Objectives. To assess the rate of seroprotection in children who received hepatitis B vaccine in the DRC context. Methods. This descriptive cross-sectional study was conducted during routine postnatal consultations at the General Hospital of Bukavu in South Kivu Province, DRC. A total of 200 infants aged 6 - 12 months and their mothers were consecutively enrolled. All the infants received the three-dose regimen of hepatitis B vaccine 6, 10 and 14 weeks after birth. The mothers were tested for hepatitis B surface antigen and HIV, while HBsAb levels were measured in the infants to determine immune response. Results. Seroprotection was achieved in 84.5% of the infants. No maternal (age, parity, duration of pregnancy, HIV and HBV status) or infant (sex, weight at birth) factors were found to be associated with absence of immunological response. Conclusions. The study demonstrated that the rate of seroprotection in the current vaccination programme against HBV in DRC was lower than desirable but comparable to rates reported in some other African countries. Further studies are needed to assess this finding and to evaluate ways to optimise the seroprotection rate.