An ascertainment of the level diphtheria antibodies in 130 children, 7 to 10 years old, in the city of S. Paulo (Brazil), revealed susceptibility in 31% of the 7-year-olds, 14% in the eight-year-olds, and 5% in the nine-year-olds. All ten-year-olds had protective circulating antitoxin at levels superior to 0.01 IU/ml. Analysis of the results thus showed that susceptibility varies inversely to age. In the population examined, the mean diphtheric antitoxin content oscillated between 0.0385 and 0.1315 IU/ml of serum.
Diphtheria; Diphtheria; Diphtheria antitoxin; DTP vaccination; Immunity