Dense population helps to explain # of cases, not necessarily mortality rate.
With dense populations come people of all types. Immune deficient, obese, diabetic, underlying heath issues, and in large numbers.
Its not only the statistical density of the population, but the way the older architecture forces people closer. Everything in NYC is more closed in and crowded than in almost any other U.S. city, from subways, to elevators, to hallways. I can go in a grocery store in my city and never come within eight feet of another shopper, in NYC you are forced to rub shoulders with strangers constantly, in stores, on the sidewalk, and just about everywhere.
Yeah, thats a good point.