THE PREVENTION OF PNEUMONIA BY INOCULATION

An able clinician and investigator whose interest has centered chiefly on the pneumonia problem remarked recently that "the more cases of pneumonia he treated the less treatment they got." It was a healthy confession of our present limitation in therapeusis which only adds emphasis to the value of the preventive measures that have been developed during recent years. To this advance American medicine has contributed its full share.

Following the promising but inexact experiments of Wright in South Africa, it will be recalled that Lister¹ carried out prophylactic immunization in a large number of Rand mine workers, using a composite vaccine made from pneumococcus types prevalent in that region. Lister at first tried intravenous injections; later, however, he found that subcutaneous injections were sufficient to establish an immunity against infection. This protection was almost 100 per cent. efficient against the particular types of pneumococci used in the vaccine, thereby