Live oral typhoid vaccine Ty 21 a. An original method of manufacturing and distribution

Oral immunization against typhoid using Ty 21 a strain did not meet the anticipated success. This vaccine is too expensive for countries which actually need immunization. The suitable form of the vaccine is not yet clearly defined. Our proposal therefore is to give up freeze-drying and to use fresh suspended live bacilli. We have established that this form is stable enough (at least one week at + 4 degrees C) to allow necessary controls and good dispatch. More, the colonization of digestive tract should be easier when the vaccine is given as a liquid than as capsules with a dry content.