Immunity to tetanus and diphtheria in various age groups of the Polish population.

The concentration of tetanus and diphtheria antitoxins was determined in 279 sera of 18 to 81-year-old women and 509 sera of 22 to 46-year-old men. Tetanus antitoxin content was determined also in 246 samples of fluid from human placentas and 428 lots of commercial human normal immunoglobulins. Immunity to tetanus was clearly age-dependent: in younger age groups the percentage of immunized persons amounted to 90%-100%, in middle-age groups to about 80%, and at age above 60 to about 25%. The findings are in agreement with age-dependent incidence of tetanus, which has become now in Poland a disease primarily of older people. Two groups of the population are now protected against diphtheria: a younger group under 20, and an older one above 40. Immunity in younger age groups was induced by artificial immunization, and among older persons by natural immunization through contact with diphtheria bacilli during severe diphtheria epidemics in the past. Between these groups, gaps exist including 20-30 years of age, who are sensitive to diphtheria.