Evaluation of Diphtheria Toxoid Preparations and Methods of Immunization

Abstract

Diphtheria toxoid was administered to 1,978 Schick-positive children (90% under 10 yrs. old) as follows: 461 received toxoid, 8-1/2 a. u. per ml.; 712 received the same preparation plus 0.2% alum; 576 received another toxoid, 71/2 a. u. per ml.; 229 received a concentrated toxoid, 30 a. u. per ml. Results were evaluated on the basis of Schick tests made 1, 2, 6 and 12 mos. after the last injection. The unconcentrated toxoids proved preferable to the concentrated preparation used. Toxoid plus alum produced the highest degree of immunity in the shortest time. Two 1-ml. doses of toxoid with 0.2% alum are recommended for all practical purposes, although a slightly higher % of reactions is encountered than when 0.5 ml. is given. It is suggested that the first injection be given simultaneously with the Schick test for children over 5 yrs. old, who have not been previously immunized, to keep the no. of visits to a min.