Diphtheria vaccine for adults.

A low dose (1.5 Lf) diphtheria vaccine for use in adults was given to 310 university student volunteers whose diphtheria antitoxin titres were less than 0.1 IU per ml. The incidence of adverse reactions was low. Postimmunisation blood samples taken from 134 of the students showed that in susceptible vaccinees the vaccine induced titres of antitoxin were consistent with protection and that it boosted the titres of those whose immunity was low.