Further studies on BCG vaccine prepared by tween 80 method with particular reference to effect of freeze-drying.

The immunizing potency of liquid BCG vaccine prepared by the Tween 80 method was compared with that of control vaccine prepared by the usual grinding method. The former vaccine revealed higher immunizing properties than the latter although its inoculation dose was only one-fifth as great.With sodium glutamate as adjuvant, freeze-drying was carried out on both vaccines. The viability of the resulting dried product was higher with the Tween 80 vaccine than with the control vaccine up to 12 months' preservation at 5 degrees C, and the allergenic potency of the dried Tween 80 vaccine stored at 5 degrees C was higher than that of the control vaccine. When the dried vaccine was preserved at 37 degrees C for a long period, the degree of decrease in viability was more marked in the Tween 80 vaccine than in the control vaccine.