Combined diphtheria-tetanus immunization of adults.

The administration of a combined adult-type diphtheria-tetanus vaccine to a group of 35 adults seeking booster tetanus immunization produced a secondary immune response to the diphtheria antigen in 26. A satisfactory response to the tetanus antigen was noted in all those who gave a reliable history of active tetanus immunization, including eight individuals who had not received a dose of toxoid for 25 to 28 years. No systemic reactions were observed, but significant correlation was found between local reactivity and a high post-booster titre of tetanus antitoxin. Selective use of the combined vaccine instead of tetanus toxoid alone offers a means of raising the diphtheria immunity in the adult population.