Effect of Glass on pH-Dependent Stability of Typhoid Vaccine

Abstract

Vaccines made from the Ty-2 strain of Salmonella typhosa were tested periodically for stability of pH and of potency. The acetone-treated cultures prepared in buffered saline solutions retained potency beyond 30 months of storage at 0 to 5 C. Similar vaccines in unbuffered saline solutions lost potency coincident with increase of alkalinity. Vaccines packaged in United States Pharmacopeia borosilicate glass vials retained potency and pH stability, whereas those in Type III United States Pharmacopeia soda-lime glass vials were less stable.