You don’t need massive influx of cases to cause a problem. All it takes is a doubling of people who come to the hospital with viral pneumonia for a prolonged period of time, maybe from 2-3/day to 4-5/day for a moderate sized hospital. They have to be sorted into corona patients and non corona patients so that they can go into appropriate wards. The worst case is putting a corona patient into a non corona patient ward. Then you could end up with a Kirkland nursing home type outbreak. The immediate problem is the sort. There are very few places where the test can be performed in a day. My state lab has backed up from 1-2 days to 2 days plus. The commercial labs have backed up from 3-5 days to 10 days plus. What do you do with the viral pneumonia patient now? You put them in the corona ward to be safe, where they will cause usage of masks whether they are truly a corona patient or not. After 3 days, test comes back negative. That patient is moved out. Meanwhile, the small bump in total patients continues. New patients are coming in, masks are in short supply, and test turnaround is increasing. At some point, testing is meaningless because after two weeks, patients have either gotten through the worst of it on their own or they are in really bad shape. That’s the problem.
It’s not a dramatic failure like an earthquake or flood. It’s more like termites or rust. It’s looks good from the outside until it doesn’t work, and then it falls apart slowly, then quickly, and there is nothing anyone can do.