@tylercowen: "By the way, the mounds of evidence (testing data, not all public) are piling up against the “so many of us already have been exposed” theories."

I agree (1/2) https://marginalrevolution.com/marginalrevolution/2020/04/monday-assorted-links-249.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+marginalrevolution%2Ffeed+%28Marginal+Revolution%29

Here's why I think it's nearly impossible that covid19 started circulating in Nov. & has already infected a substantial fraction of the population: if that was true, NH and IA should have seen their health systems collapse before NYC.

Thousands of reporters, hundreds of rallies

The candidates and their staffs were all going back and forth to various states, holding mass rallies, followed by huge media operations.

If covid19 had been widespread in any city, it would have ended up in those two states, and rocketed through the whole population.

*If* covid can do to any place what it has done to NYC, it should have done it to Iowa's counties, which are full of old people and have little ICU capacity. Iowa's health care system did not collapse, QED, there was no widespread US circulation of covid19 in late January.

If covid19 was not widespread in January, then it is not mathematically possible that we've all had it.