From Jan. 1, 1927, to July 1, 1930, there were 1,280 undergraduate nurses on duty in the Cook County Hospital. Practically all were exposed at some time in their stay to scarlet fever and diphtheria. The majority were tested for susceptibility to scarlet fever and diphtheria and immunized if susceptible by the Preventive Medicine Clinic of the Scarlet Fever Committee. Others were not tested or were tested but did not complete their immunization. These constitute a satisfactory control group.
RESULTS OF SKIN TESTS FOR SUSCEPTIBILITY TO SCARLET FEVER
Of the 1,280 nurses, 913 received the Dick test; 380 (41.6 per cent) were found susceptible and 533 (58.4 per cent) were found immune to scarlet fever. None of those found immune on original tests contracted scarlet fever. During the same period, fifteen cases occurred among a group of 449 who were either not tested and not immunized at all or incompletely
RHOADS PS. SKIN TESTS AND IMMUNIZATION AGAINST SCARLET FEVER AND DIPHTHERIARESULTS IN NURSES OF COOK COUNTY HOSPITAL. JAMA. 1931;97(3):153–156. doi:10.1001/jama.1931.02730030003002