The futility of the usual forms of treatment during the epidemic of influenzal pneumonia was early manifest. With a fatality much greater than our common pneumonia, it suggested the pandemics of old when "the pestilence stalked at noon day through the city, and the doomed inhabitants fell like grass beneath its scythe."
Though the causal agent was undetermined, it seemed that the serum of convalescents might possibly contain antibodies in sufficient quantities to influence favorably the course of the disease.
Serum from patients convalescent from scarlet fever was found by Huber and Blumenthal, Von Leyden1 and others to be of some therapeutic value in that disease, and both experimentally and in human beings the serum of poliomyelitis convalescents is beneficial if used early.2
Richardson and Connor3 recently demonstrated that the serum of patients convalescent from measles conferred a certain amount of immunity.
We did not know at