Reimmunization Against Diphtheria of Previously Immunized Children

Abstract

Observations have been made of the reimmunization response of 808 children who had been immunized previously. Diphtheria antitoxin immunity, regardless of the immunizing procedure, is not permanent. As time goes on the antitoxin content of the blood is reduced and it is apparent that progressive reduction of antitoxin content, though slow, is very definite. Reimmunization with fluid toxoid or alum-precipitated toxoid is highly effective, and 1 small dose produces a response in a satisfactory proportion of the children. General allergic reactions were not observed in the entire group, and the % of local reactions was not severe enough to discourage reimmunization. Previously immunized children who had lost all demonstrable antitoxin responded much better to a single injn. than children not previously immunized, and without demonstrable antitoxin. Reimmunization of children 5-6 yrs. after immunization in infancy appears to maintain the blood antitoxin at a good average level. The alum-precipitated toxoid was somewhat superior to fluid toxoid as a reimmunizing agent, although its comparative effectiveness as an agent for primary immunization is much more striking.