My guess is something like herd immunity is starting to show up in R0 in NYC. https://twitter.com/NateSilver538/status/1252680119489003521

Serological testing in NYC seems pretty close to biggest value-add study at this point. Very different from California, where the low base rate makes false positives a serious issue that complicates analysis.

If >40 % of New Yorkers have had Covid-19, infection fatality rate would be < 0.5 %. At that point, the best NYC solution would probably be for young & healthy people to complete the herd immunity.

And we may just be one anti-viral victory away from making that the ideal solution around the world.

If < 20 % of New Yorkers have had Covid-19, we are in trouble & better get a test & trace system in place.