Earlier quoted context omitted.
I had wondered how the current new cases / day in NY were so low as compared to other areas. This seems likely to be at least part of it. What's the theory on why other places that were hit hard early are still quite high...like California? Lower density?
California wasn't hit very hard early. In terms of total reported cases, they're only just now starting to catch up with New York (21 per thousand for the state vs 17 per thousand for California) - and as we catch up we've had a pretty sharp improvement from the peak in July. The theory is that California flattened the curve in the original sense, delaying the peak in order to ensure it's moderately lower and protect…
The takeaway to me is that unless you are willing to exert extremely strict border controls, localized quarantines and hard lockdowns of hotspots, and pervasive test & trace, indefinitely, then you wont keep Rt below 1 without the benefit of some herd immunity.
Hence lockdowns should either be as minimal as possible, encouraging low-risk populations to be out and about while high-risk populations shelter.... Or, you need an extreme and extraordinary response until widespread effective vaccination.
Small island nations may find they can choose the second path (although it’s not guaranteed, Hawaii has recently failed at it) but the vast majority of the world should choose the first.
And we should stop politicizing it, because largely everyone is in the same boat and will hit all the same endpoints.