In spite of the wealth of statistics collected from such reliable sources as the European and United States army reports, considerable difference of opinion exists as to the advisability of giving antityphoid vaccine to persons presumably infected. Wright1 in his earlier communications emphasized a negative phase directly following administration of vaccines, and advised against their use in the presence of an epidemic. Leishman2 and others are not positive of the existence of a negative phase and Russell3 in a recent article insists that a negative phase does not exist. He notes, however, that a single injection of vaccine confers little or no immunity to typhoid fever.
A recent epidemic of typhoid fever at the St. Louis City Hospital offered us further opportunity for study along these lines.
There are, exclusive of patients, about 400 people in the personnel of City Hospital. This epidemic was traced to the