Whooping cough is an important disease among young children. The dangers from complications warrant any effort to protect young children from becoming the victims of this infection. The difficulty of early diagnosis and the unsatisfactoriness of the measures which have been used in years past to obtain active immunity have stimulated further inquiry into the matter of passive immunization by means of the blood serum of persons who have recovered from the disease. The successful use of convalescent scarlet fever serum suggests that human serum from persons who have recovered from whooping cough may be useful in decreasing the incidence of the disease among the very young.
To measure the value of human blood serum in prophylaxis for young children who have been exposed to whooping cough, a group of control children must be selected who are similar in all respects except that they have not had this serum. To