Oli A. N., Oli A. H., Nnadozie O. J., Uzodinma S. U., Ele G. N., Okeke I. J. and Esimone C. O.
The present study was to give an over-view of the potency of the vaccines used for National Immunization programme using Congo red binding test and to provide a quick method of estimating the stability/ potency of the vaccines when a more rigorous method is not feasible for some reasons. This is an experimental study carried out in the department of Chemical Pathology Laboratory of Nnamdi Azikiwe University Teaching Hospital, Nnewi between December 2011 and September 2012. The solutions that contained the vaccine samples and the controls were incubated at 37â°C for 48 hours, centrifuged and the absorbance of the supernatant fluid measured. The absorbance at 480nm of unbound Congo red dye in Phosphate buffered saline solution in the absence and presence of the vaccines were measured and recorded. The amount of Congo red bound was calculated by subtracting the absorbance of Congo red in the supernatant (vaccine present) from the absorbance of Congo red in PBS solution (vaccine absent). The absorbance of the different concentrations of Congo red dye in PBS alone (i.e. unbound dye) was determined before each set of experiment. The use of Congo red binding test may provide a quick method for the estimation of the potency and stability of immunization vaccines. By this Congo red binding assay, the vaccines tested passed as there was a continuous increase in the amount of dye bound by the vaccine samples. The vaccines tested are potent enough to be used for immunization. It was observed at the time of vaccine collection that the storage facilities in all the three states’ vaccine stores had adequate power supply - the National Electricity supply being supplemented with standby Generators.
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