Plot hole: When someone is in a coma for 28 days, the hospital would have AT LEAST have catheterized said person, however when Jim wakes up in the hospital he is not attached to anything but an IV.
Suggested correction: What happened when Jim was admitted is never revealed. Being that there is nothing to show what happened when he was admitted its impossible to say certain procedures would have been followed or more simply the hospital might have not undertaken them. More importantly we don't know when the virus hit certain areas. In addition Jim was taken in around the time the virus was first starting to spread and hospitals would be the most likely place someone infected would be taken to so many working or staying there would have been the first to have been infected. With that scenario the staff at the hospital might have neglected some of their patients because of how quickly the virus spread.
If the hospitals would have been some of the first infection sites, why would Jim have survived the entire 28 days? I doubt someone was refilling his IV on a regular schedule if the patients are becoming violent animals, which would suggest he would have died of dehydration before starvation would have gotten to him. Also, why would those infected ignore Jim while he was comatose? Would it not be 'sporting'? Given how instinctual they seem to become I don't see how comatose would be any different from intoxicated or deeply asleep. Did all of those sorts avoid infection as well?