Antitoxin responses in the elderly to tetanus-diphtheria (TD) immunization.

A high per centage of reported cases of tetanus and diphtheria in the United States occurs in persons over 60 years old. The sera of 69 elderly persons, mean age 80 years, were tested for prevalence of tetanus and diphtheria antibodies, and only 51% and 59%, respectively, had protective levels (greater than or equal to .01 AU/ml). In a prospective study 27 elderly volunteers were given 0.5 ml tetanus-diphtheria (Td) toxoid twice, seven months apart. Before toxoid 26% and 59% of persons had protective antitoxin levels against tetanus and diphtheria. After one dose the per cent protected rose to 42 and 88. After the second dose all persons immunized had protective levels. No subjects had significant side effects after either dose. These data demonstrate that many elderly persons lack protection against tetanus and diphtheria and document that two doses of Td toxoid would confer immunity to virtually all such persons.