Evaluation of the Efficacy and Safety of Hepatitis B Vaccines Sold in Open Markets in South Eastern Nigeria

Abstract

This study was carried out to determine the compliance of different brands of Hepatitis B vaccines marketed in open markets across South-Eastern Nigeria with Pharmacopoeial standards for safety and immunogenicity. Four different commercial brands of hepatitis B vaccines (Hepavax, Euvax, Sii and Engerix brands) were purchased from open markets across the five states of South-Eastern Nigeria. The toxicity and immunogenicity of the different vaccine brands were evaluated using animal model. Using 70 mice, the immunogenicity of the vaccines was evaluated by quantifying Hepatitis B-specific antibody levels after immunization. Similarly, safety of these vaccines was evaluated by investigating the sterility, endotoxin levels, and changes in the weight, liver enzymes (ALT) and white blood cell count (WBC) The various brands of hepatitis B vaccines appeared sterile and conformed to Pharmacopeial requirements for parenteral products. All the vaccine samples were all endotoxin-free and nontoxic. The total white blood cell (WBC) count showed no significant increase at 18 and 72 hours in the test animals after administration of the vaccines. Except in animals immunized with Euvax 1 brand, there was no significant change (P < 0.05) in the weights of the test animals at Day 8 after immunization compared to the control. There was no statistically significant difference (P > 0.05) between the ALT levels produced by various vaccine brands. All the vaccines induced the production of Hepatitis B specific antibodies. All the tested brands appeared immunogenic. However, while three brands conformed to the Pharmacopeial safety profile, more studies are needed to further evaluate the safety of Euvax because on unsatisfactory weight changes observed in this study. Keywords: Hepatis B Vaccines; Nigeria; Commercially Available; Efficacy; Immunogenicity; Safety;