Stability characteristics of freeze-dried human live virus vaccines

Freeze-drying (lyophilization) of biologically active materials such as human live virus vaccines is an accepted method of preserving potency. Since freeze-drying does not assure total stability, a formal system of monitoring stability, i.e., potency, has been established. Two experimental desings are utilized: (1) Long term studies to duplicate normal use storage at -20 degrees C and 2-8 degrees C and (2) Accelerated studies which predict long term stability through regression analysis using the Arrhenius equation. Data summarizing stability experience over a long period of study will be presented.