Effect of a Stimulating Dose of Pertussis Vaccine on Children Previously Immunized

Abstract

During the course of study on the agglutinin response to pertussis vaccination in a group of Chinese children, it was noted that in every case the agglutinin titer of the blood sooner or later reached its height and then began to decline. This observation aroused our interest to try out the effect of a stimulating dose of the pertussis vaccine on the titer of the specific agglutinin, particularly in view of the successful results of restimulation in the case of active immunization against typhoid, 1 diphtheria and tetanus. 2 Five infants varying from 9 months to a little over one year of age in whom a negative history of pertussis infection in the past is reasonably sure were chosen as subjects for study. The first 2 infants were vaccinated according to the procedure recommended by Sauer; 3 namely, bilateral injections of 1 cc each into the deltoid muscles on the first occasion followed by similar injections of 1.5 cc each one and 2 weeks later respectively. To the third infant, similar doses were given with the intervals between successive injections lengthened to 3 weeks. The fourth and fifth infants differed from the third one in that they failed to come back for the third dose of vaccine. The vaccines used were prepared from cultures of the strains of H. pertussis isolated from our own patients not longer than 4 months previously and kept virulent by frequent transfers on the Bordet Gengou medium plus 20% fresh, defibrinated human blood. They were standardized by turbidity method to contain approximately 10 billions of organisms per cc. Blood samples were tested at frequent intervals for the presence of specific agglutinins by means of the rapid agglutination technic advocated by Kendrick. 4

The blood of these 5 infants taken just before vaccination gave a uniformly negative result to the agglutination test.