I admit it's not very clear.
This is jargon from the epidemiologist. Case report means an individual report. That's what it means. One person would say, “Well, our study includes one case, and this person had this and this...”, and so on and so forth. This is usually not used in any kind of epidemiology.
And “hospitalized patients”, what is really meant by that is that just by the hospital diagnoses, just using the hospitalized patient diagnoses to base your report on, because you have no indication of whether or not they were exposed or potentially exposed or not, the information would be incomplete and your findings would be incomplete.
That's pretty standard in epidemiology, but that is not to—