The Effect of Low Temperatures on Vaccines of Influenza Virus and on Purified Influenza Virus

Abstract

Summary The purpose of this investigation was to obtain information on the effect of subfreezing temperatures on the destruction of the hemagglutinating capacity of influenza vaccines and purified influenza virus. Vaccines prepared by adsorption-elution showed no change in hemagglutinin titer during eight days' storage when frozen. Vaccines prepared by centrifugation showed a marked decrease in hemagglutinin titer during eight days' storage at −10 C to −20 C. In higher and lower subfreezing temperatures the destruction was slower. The effect of repeated freezing and thawing processes was comparatively small. In experiments with purified virus the hemagglutinating capacity of the virus diluted in phosphate buffer, as compared with virus diluted in buffered saline, was less stable at subfreezing temperatures and this phenomenon could be exaggerated by pH changes or by addition of formalin.