On Sept. 16, 1918, Chicago’s Health Commissioner announced that officials had “the Spanish influenza situation well in hand now.” To monitor the situation, Robertson made influenza a reportable disease, but took no further action.

Chicago’s epidemic, however, had only just begun. By September 30, there were 260 cases in the city. The large and sudden jump in new cases led Health Commissioner Robertson to order the immediate isolation at Cook County Hospital of all known cases. by Mid-October, Chicago physicians were reporting a staggering number of new cases, reaching as high as 1,200 a day and climbing.