In 1954-60 a Yugoslav Typhoid Commission showed in the first controlled field trial of typhoid vaccines, carried out in Osijek, Yugoslavia, that heat-phenol-inactivated typhoid vaccine gave a relatively high and long-lasting immunity. However, this liquid vaccine preparation was unstable and laboratory potency tests were inconclusive, and it was therefore decided that stable, dried, heat-killed, phenol-preserved vaccine be tested together with an acetone-inactivated and -dried vaccine in controlled field trials, supported in part by the World Health Organization, in Yugoslavia and British Guiana.This is report on the controlled trials organized in two Yugoslav towns, Bitola and Pristina. Three comparable groups were formed by random allocation of vaccines among 45 497 volunteers in the two towns. In each town one group received heat-phenol vaccine, the second group acetone-dried vaccine and the third (control) group tetanus toxoid. Two doses were given four weeks apart in the spring of 1960 and the vaccinated persons were followed up for 2 1/2 years. The effectiveness of the vaccines was measured by comparing typhoid morbidity rates in the three groups. It was found during an outbreak of typhoid fever in Pristina two years after primary vaccination that both the acetone-dried and the heat-phenol vaccines were effective, the former being superior.

Accident Prevention↗

PubMed1964

PREPARATION OF DRIED ACETONE-INACTIVATED AND HEAT-PHENOL-INACTIVATED TYPHOID VACCINES.

Controlled field trials of two dried inactivated typhoid vaccines have been carried out in British Guiana and Yugoslavia under the sponsorship of the World Health Organization. This paper gives details of the methods of preparation of these vaccines in such a manner as to permit of replication by others.Both vaccines were derived from the Ty 2 strain of Salmonella typhosa. For production of the acetone-inactivated vaccine, a portion of the surface agar growth of the Ty 2 strain was treated with acetone by the Landy method modified so that inactivation and handling were done in liquid suspensions rather than on a filter, and the vaccine was dried in the final containers. For the heat-phenol product, another portion of the same growth was processed by heating, the addition of 0.5% phenol and holding at room temperature for 72 hours followed by freeze-drying in the final containers. These vaccines are designed for use within a few hours of the addition of the reconstituting fluid.

Acetone↗

PubMed1963