Immunogenicity of a low-cost hepatitis B vaccine in the South African Expanded Programme on Immunisation.
Aspinall S. Kocks DJ.
Department of Virology, Medical University of Southern Africa, Medunsa.
BACKGROUND: A low-cost, 'flash' heat-inactivated hepatitis B vaccine with enhanced immunogenicity allowing for a relatively low dose (Hepaccine B; Cheil Foods and Chemicals, Korea) was introduced into the South African Expanded Programme on Immunisation during 1995 to immunise infants against hepatitis B. To determine the seroresponse of this vaccine in South Africa, a country with a high hepatitis B virus (HBV) prevalence, a field trial was conducted in a rural health clinic. METHODS: The immunogenicity of Hepaccine B, containing 1.5 micrograms/0.5 ml, was studied in 186 black infants attending the Soshanguve III clinic, north-west of Pretoria. Infants receiving three consecutive doses in the anterolateral thigh at 6, 10 and 14 weeks were monitored. The doses were administered concurrently with their routine oral polio vaccine (OPV) and diphtheria, pertussis and tetanus (DPT) immunisations. Vaccine side-effects were recorded. Blood specimens were collected 3 months after the final vaccination. Sera were tested for antibodies to hepatitis B surface antigen (anti-HBs) by IMx AUSAB (Abbott Laboratories, USA). Levels of anti-HBs were determined by comparison with standard reference preparations and expressed in mlU/ml. RESULTS: Side-effects of the vaccine were minor, with limited local reaction at the site of administration. The anti-HBs seroconversion rate was 93.0%, based on a titre of > or = 10 mlU/ml with a geometric mean titre of 257.58 mlU/ml. CONCLUSIONS: Administration of 1.5 micrograms dose of Hepaccine B at 6, 10 and 14 weeks is safe and highly immunogenic in black South African infants, and this vaccine is suitable for use in countries with high HBV prevalences such as in Africa. The use of an economical hepatitis B vaccine would greatly facilitate the prevention of hepatitis B in these countries.