[vondur]

I've also read that one of the reasons that California has relatively low infection numbers given it's circumstances, may be do to the fact that Covid-19 had been spreading earlier in the year. Many people may have been unknowingly infected, and either have recovered and have immunity, or unfortunately may have died from it.

[vanniv]

It may be so.

Although, it seems apparent that there were not millions of cases before we started looking, given that hospitals here were not overrun like they were in New York.

About a month ago, I did some poking around with the CDC FluView statistics (in-season estimates of influenza and all-cause-pneumonia deaths)

The conclusion that I came to was an upper bound on undetected COVID cases before 3/1 of 300k.

More than that, and the hospitalization and death rates could not have hidden in the flu and pneumonia data.

300k extra recovered cases, even if they were all in CA, would not be material in terms of new immunity.

Unless the Asia-origin strain we had was much less dangerous than the European-origin strain in NY (in which case more cases might hide in the data) -- but that is a pretty tall set of assumptions.

[Gibbon1]

My take the rate of serious illness and death due to COVID19 is a bounded parameter with a linear range. The infection rate is currently unbounded and logarithmic.

Ain't got much wiggle room to work with there. You have to pretend the morbidity rate is 20 to 50 times lower than the known lower bound (3-5%). So doesn't square.