A controlled field trial and laboratory study of five typhoid vaccines in the USSR.

A controlled field trial of typhoid vaccines was carried out in the USSR in 1962. It was the fifth and last of a series. Five preparations were tested, the most effective being a heat-killed divalent vaccine prepared from aerated broth culture. The results of a laboratory study of the vaccines were not in complete agreement with the data from the field trial. No correlation was found between the effectiveness of vaccines and the data from laboratory tests as to their potency, and the authors suggest that differences in effectiveness may be due to varying degrees of damage to biological components during the different production processes. The effectiveness is also sensitive to dosage.