Assessment of effectivity of oral killed typhoid and paratyphoid B vaccines and aerosol chemical typhoid vaccine in controlled field trials.

A total of 3 controlled field trials were carried out. One of them (1963) showed that aerosol chemical typhoid vaccine did not protect vaccinated subjects from the disease. Two other tests (1964 and 1965) assessing the effectivity of killed orally administered typhoid vaccine revealed a short term (up to 3 months) protective effect expressed by an effectivity coefficient of 45%, fiducial limits being 8-70%. In the assessment of oral paratyphoid B vaccine, the difference in morbidity in the experimental and control groups was statistically insignificant due to a small number of cases of disease.