How much Immunogenic are the Oral Polio Vaccines Sourced from the Central Cold-chain Facilities in South-Eastern Nigeria?

Author(s): Angus Nnamdi Oli

Context: There is need for continuous monitoring and validation of pharmaceutical products (including vaccines) in circulation in every country. Vaccines must be maintained in cold-chain from the manufacturer to the end user. Aims: This study aims to validate the Oral Polio vaccines sourced from the Central Coldchain facilities and used for vaccination programmes in South-East, Nigeria. Settings and Design: The Study was an experimental in design and performed in laboratory. Methods and Materials: The immunogenicity test was done using Antibody Induction Method. This involved measuring the neutralizing antibodies in a control group (mice given Oral Polio vaccines stored at 37�°C for 12 months) and test group (mice given Oral Polio vaccines sourced from South-east States) after 30 days using Enzyme-Linked-Immunosorbent-Assay technique. Statistical analysis used: One-Way Analysis of Variance (ANOVA), Dunnettâ��s Tests of Multiple Comparison and Bartlettâ��s test for equal variances were used. Results: All the vaccines used were within their shelf-life. The Mean �± Standard Deviation of the temperature of the vaccines at point of collection was -19.60 �± 0.56, before storage it was -13.00 �± 3.74 and at storage facility, it was -19.80 �± 0.60. The mean antibody titres evoked by the Oral Polio vaccines from Enugu, Ebonyi, Imo, Anambra, Abia and then the control were 22.90, 23.18, 18.55, 17.12, 17.38 and 7.36 IU/mL respectively. One way analysis of variance shows that there is statistical difference (P value=0.0026) in the antibodies titres produced by the vaccine samples. The antibodies were enough to confer protection against the target diseases. Conclusions: This study showed that the oral polio vaccines from the central cold-chain facilities in south-eastern Nigeria were still in good condition as at the time of sample collection and were immunogenic enough to induce protection. The cost of immunizing a child is heightened by the inbuilt cost of maintaining alternative power supplies to the national power grid. It is, therefore, recommended that vaccines not requiring cold-chain storage is urgently needed in resource-limited countries to reduce the high immunization cost brought about by cold-chain maintenance system. This will strengthen and enhance the process of achieving and sustaining the eradication of infectious diseases, especially polio, in developing countries.
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