Dude, they can't even sort out their air.
China is exposed because if it hits in the major population centers on the east coast of China (pacific coast) it is going to be massive. China also has tons of slums. And there is a huge black market, well, not black market as you would imagine it, but shops, vendors and service providers of all sorts that nobody regulates. If it hits it in the middle of village in god knows where, no problem.
India is also exposed for the correct reasons you stated and because of their cultural norms. They don't kill rats, they bathe in the rivers in common and they usually have very large families within a very small space.
And in Europe there is 1 reason why it could be very bad, and it's also a reason that applies to China and India and one that the USA doesn't have to worry about: public transport. For once, the USA's complete disregard for energy efficient, pro-enviromental methods of transportation pays off. In Europe and china and India, public transport is huge. Granted, in china and india things are always more crowded than in europe but in europe it gets pretty crowded. I've been a sardine in a bus quite often. Granted, eastern europe not the same as western europe.
It's why I have bought both gloves and masks and carry them on my person (so not wear them ,but have them with me) at all times when I'm going out these days. For one, to avoid the flu season (which I failed at, I am currently sick, last days of my flu -> granted, i got my flu at work not on the bus) and to avoid other diseases should they make their appearance.