On the evening of March 12, about 36 hours after the initial call to the health department, TDH staff conducted a matched case-control study among students at the university. Ill students (reported from emergency rooms and the Student Health Center) who could be reached at their dormitory rooms were enrolled as cases. Dormitory roommates who had not become ill were asked to serve as matched control subjects. Investigators inquired about meals the students might have eaten during March 5th-10th and where the foods were eaten. All information was collected over the telephone.

What are the advantages and disadvantages of undertaking a case-control study instead of a cohort study at this point in the investigation?