Quality Evaluation of Rubella Vaccine used in India

Abstract

Objectives: Cold chain maintenance is essential to ensure vaccine quality till it reaches the end user. In tropical countries like India with hot and humid environment, the transport of vaccines with required cold chain is comparatively difficult. Also, the efficacy of live viral vaccines is dependent on proper attenuation of vaccine virus. The present study was carried out to analyse the quality of 41 batches of rubella vaccine stored at 2-8C and their thermostability after exposure at 37C for 7 days, as such no study is published from India. Accordingly, the trends for the potency and stability titres of these batches of rubella vaccine were analysed during the present study. Method: All the Rubella vaccines batches were tested in triplicates against reference vaccine as per the WHO formula. The number of wells showing cytopathic effect was counted and titres were calculated using Spearman-Karber formula. The geometric mean titre was calculated for the triplicate readings. The assay is considered valid only if confidence limits (P=0.95) of the logarithm of the virus concentration is greater than 0.3. WHO criteria state that minimum virus concentration should be 10^3.0CCID₅₀ per human dose for both exposed and non-exposed rubella vaccine. Also, after incubation the loss in titre should not be more than 10^1.0. Result: The potency and thermostability titres of all the batches tested were found to be between 10^3.467 to 10^4.03 and 10^3.276 to 10^3.72 respectively and were well within prescribed specifications of WHO. Conclusion: Potency and thermostability of the rubella vaccine tested were found in the acceptable range indicating rubella vaccine used in India is quite potent and thermostable.