^^^ Great. I actually had not fully understood the CFR calculation you had. So, you are actually talking about death per infection (as in sero-surveys) and not the "sufficient level of infection to be tested and counted," which I was recommending. Nice to know that the quick calculations were in the ball park. Actually it gives me some relief, to finally start getting an idea about what the heck is going on!
The scientists are right about infections. But like I said, they should shut the hell up because it is rather irrelevant in the case-count discussion! ... It is relevant though on predicting the peak etc because I think the various areas do need to get up to certain levels of infection. That is not the classic "herd immunity" but just a level of immunity for a slow-down of the growth to the level where the test-trace-contain operations have a chance to start isolating growth areas and dropping the numbers.
That also explains, possibly, why Europe was able to drop it because it pretty much had got everywhere and reached 10-15% infections in a hurry before they even got to doing anything. The thing is that EVERY European country is directly connected internationally (air and train travel) unlike the US and India where the domestic travel needed to take it to various places and cause the growth.' Once they started tracing and containing, it was going to stop in many neighborhoods, which it did.
The reason we are not getting a peak is actually because we prevented the 10-20% infection rate from happening, with an early lockdown. But in places like Ramagunj in Jaipur and the pockets of Indore, Agra, etc, such levels of immunity happened, and then it was easier to get a drop from the testing/tracing process. Dharavi probably has that level of infection too.
So it is a good thing to know that Kolkata showing 15% infection and no calamity has happened.