Comparative analysis of the intracerebral mouse protection test and serological method for potency assays of pertussis component in DTP vaccine

The aim of this study was to compare the PSPT standardized in-house as an alternative to MPT for potency assays of pertussis component. Statistical analyses have showed similar pertussis potency values when PSPT was compared to MPT. Significant correlation between the potency results obtained by in vivo and in vitro assays was also been observed. Results by PSPT have demonstrated reproducibility and accuracy for potency pertussis control and this approach has been considered promising for use at least during the steps of production.

Using physical method to determine the previous freezing of absorbed DTP vaccine

Absorbed DTP vaccines in the same Lot (produced by IVAC, Nha Trang) were kept at 4°C, -5 +/-10oC, -20°C on 2, 3 and 6 hours. After being thawed completely, the vaccine containers were vigorously shaken and the contents were examined for physical changes. The results showed that the containers kept at 4oC had no physical changes; the containers kept at -5 +/-10oC, 20°C for 6 hours had significant changes such as agglomeration, floccules or granular matter, and sedimented rapidly. It is suggested that structure of aluminum adjuvant in DTP vaccine is changed. The containers kept at -5 +/-10oC, -20°C for 6 hours can be considered as the positive control and the shaking test can be used to determine the previous freezing of adsorbed DTP vaccines.