[Farm93]

I would think that upstate NY's number is at least somewhat influenced by proximity/interaction with NYC residents.  So even 3% might be too high to use nationally.

Not really... the suburban counties near NYC were in their own category.

Those in upstate NY really are more like Vermont than NYC.

There might be a bit of NYC residents using winter cabins or going to ski resorts that would cause spread to those areas, but probably no more than the amount of spread caused by LGA or JFK to ATL or DFW.

The upstate NY that was in the Upstate NY is likely largely comparable to TN, KY, the Alabama-like parts of PA, etc.

Again, sure would be nice for the Federal government to start widespread antibody testing or even sampling of the population to get a sense for the true size of that denominator. 

Why?
If 10 or 15% of the USA population has antibodies the stock market would soar so quickly and people would learn the virus is not really as deadly as we suspect right now.
For our stock market and economy obsessed POTUS testing just 3,000 US citizens could do more than 20 or 30 more daily briefings.  

It seems like a better miracle play than dreaming about a miracle drug or the COVID19 vanishing from the planet before the end of April.

[Farm93]

I would think that upstate NY's number is at least somewhat influenced by proximity/interaction with NYC residents.  So even 3% might be too high to use nationally.

Not really... the suburban counties near NYC were in their own category.

Those in upstate NY really are more like Vermont than NYC.

There might be a bit of NYC residents using winter cabins or going to ski resorts that would cause spread to those areas, but probably no more than the amount of spread caused by LGA or JFK to ATL or DFW.

The upstate NY that was in the Upstate NY is likely largely comparable to TN, KY, the Alabama-like parts of PA, etc.

Again, sure would be nice for the Federal government to start widespread antibody testing or even sampling of the population to get a sense for the true size of that denominator. 

Why?
If 10 or 15% of the USA population has antibodies the stock market would soar so quickly and people would learn the virus is not really as deadly as we suspect right now.
For our stock market and economy obsessed POTUS testing just 3,000 US citizens could do more than 20 or 30 more daily briefings.  

It seems like a better miracle play than dreaming about a miracle drug or the COVID19 vanishing from the planet before the end of April.