Antibody Response to Tetanus Toxoid 15 Years After Initial Immunization

Abstract

Serum tetanus antitoxin levels were determined by a standard mouse protection test on 104 World War II veterans who had been immunized 15 or more years previously during active military service. A standard booster dose of fluid tetanus toxoid was administered and serum drawn at 4, 7, and 14 days for tetanus antibody determination. Only 8 of the 104 subjects had no detectable antibody 15 or more years after immunization; 45 had at least 0.1 units of antitoxin per ml. Of the patients tested 4 days after toxoid injection 84% showed no change in titer; the remainder showed slight increases or decreases. Seven days after booster injection 70 of 81 patients (86%) showed a significant rise in antibody level, and all but one of these had titers of 0.1 units per ml or greater. Fourteen days after booster injection 58 of 59 patients tested showed marked increase in titer over base line levels. The one patient showing no increase in antibody titer had a high base line level and it is questioned whether he actually received his booster injection. It is considered that except for grossly contaminated wounds, a single booster dose of tetanus toxoid provides ample protection against clinical tetanus for all persons immunized at any time up to 15 years previously, and probably for considerably longer periods.