It hasn't.
FFS, you still have a fundamental misunderstanding of "herd immunity".
The lowering death rate is a function of science and medicine getting a handle on treating the infected.
By your understanding there shouldn't be any new cases in NY, as everybody is immune.
Let me Google that...
Nope.
4100 new cases in the last seven days:
https://www.google.com/url?sa=t&sou...gQIBRAL&usg=AOvVaw0ICtmRdMdeA_JdrHEGPhVO&cf=1
How is that possible when everybody is now immune?
Hell, how is that possible when enough have immunity that there isn't enough virus present to result in new infections? (Which is what "herd immunity" actually means.)
You are wrong regardless of what definition you use.
(Well, I guess a case could be made that your herd is immune to any information that comes from anywhere but conservative media.)