Scholars tend to go down rabbit holes and don't see the obvious.... The smoking rates come from WHO, The population density is just pure math, 60 million people in a country 2/3 the size of California. High speed trains are all over Italy, we don't have that in most of the United States, but New York certainly does, the SUBWAY is ground zero for the spread of this in New York, I can guarantee that. Of all the factors, the population density, and public transit are by far the biggest (New York metro ares has double the population of Lombardy). One other factor that I didn't mention, is that culturally, Italians have less of a personal bubble, they will Kiss and hug in a situation where an American will shake hands. New York City has almost half of the infections in the whole country, what is different there than the rest of the US? The density, the public transit, and the prevalance of apartment living. Los Angeles' rate is much lower, because those same issues are not at play. And AMEN about the bidet. Americans and their sole use of toilet paper is filthy, IMO... never understood it. I've been talking about that on social media, and people think I'm nuts. There is even ANOTHER factor that I didn't mention, Italian meet after work in town squares and socialize with each other, as opposed to America where they tend to keep more into their own house and space.