Between May 27, 1934, and July 30, 1935, 483 children of Cleveland from 6 to 15 months of age were given pertussis vaccine prepared from strains of Haemophilus pertussis recently isolated and proved to be in phase I of Leslie and Gardner.1 The children were selected from the active registers of five child welfare stations of the Cleveland Division of Health. As a control group 496 children comparable in age and other pertinent characteristics were selected from the same sources.
To insure reasonably complete and equivalent registration of cases for each group, reports of pertussis to the Division of Health were scrutinized currently, but major emphasis was placed on an independent system of notification. To the age of 15 months, the children of both groups were kept under observation by the nurses of the child welfare stations, those who failed to attend during any four week period being visited
DOULL JA, SHIBLEY GS, HASKIN GE, BANCROFT H, McCLELLAND JE, HOELSCHER H. ACTIVE IMMUNIZATION AGAINST PERTUSSISFINAL REPORT ON THE CLEVELAND IMMUNIZATIONS OF 1934-1935. Am J Dis Child. 1939;58(4):691-698. doi:10.1001/archpedi.1939.04380010001001