Enhanced stability of meningococcal polysaccharide vaccines by using lactose as a menstruum for lyophilization.

A comparison is made between lactose and mannitol as additives for the lyophilization of meningococcal polysaccharide vaccines. From the stability data obtained on storage at high temperatures, it is concluded that vaccines containing lactose as a menstruum for lyophilization are much more stable than vaccines prepared with the currently used additive, mannitol. The enhanced stability of these vaccines makes it possible to store also group A vaccines at 5 degrees C instead of at -20 degrees C, and to use them in places without freezing facilities.