Potency/immunogenicity profile of DPT vaccines used in the expanded programme on immunization in South-East, Nigeria

Abstract

Objectives: This study tries to validate the DPT vaccines used in South-east Nigeria for the routine childhood immunization. Study design: The Antibody Induction Method in mice was used. The neutralizing IgG antibody titers in a control group (7 mice given DPT stored at 37°C for 1 year) and test group (7 mice given DPT vaccines from the SouthEastern States of Nigeria) were compared after 30 days post-immunization using One-Way ANOVA, Bartlett's test for equal variances and Dunnett's Multiple Comparison Test. Results: The vaccines from the States produced similar Pertussis and Tetanus antibody titers which were significantly higher than the control (P<0.0001). The Diphtheria antibody titer produced by the vaccine from Enugu/ Ebonyi States was higher than the vaccines from other States. The control produced much less Diphtheria IgG antibody titer (P<0.0001). The vaccines do not differ significantly from each other on the level of antibody titer (protection) and their individual protection can last for the maximum number of days needed for a repeat vaccination except for the control. Conclusions: There is statistical difference in the antibody titer evoked by the control compared to that evoked by the vaccines from the states. The vaccines from the States show 100% potency and immunogenicity. This indicates adequate cold-chain maintenance and monitoring of South-eastern Nigeria. Continuous monitoring of efficiency of cold- chain maintenance and vaccine potency testing would translate to good vaccine strategy. © 2013 Yousif MA, et al.