[vanniv]

I was terribly sick in early February, in CA. I went to my urgent care multiple times as I got worse.

The doctor tested me for influenza, but told me that he was seeing hundreds of patients, all day every day, with "an unusual flu" where they were mildly sick for a few days, recover, and then suddenly got much worse with high fevers and chest infections -- and most of those patients were turning up with negative influenza tests. But influenza tests have a high false negative rate, so just because I was negative on the test didn't mean anything. The doc said that this year, the influenza test only seemed to show positive for folks that had a high fever the first day of their illness (which, between you and me, is very common with influenza and very uncommon for COVID)

I was out of work for over a week, and only got out of bed when I had no choice the entire time.

None of my doctors asked me about travel or contact with recent travelers, and nobody ever even suggested getting a coronavirus test.

When I got back to work a week later, I learned that nearly 10% of my office had gotten sick either the same day as me or while I was out.

Did we all have COVID-19?

maybe. Maybe not.

None of us were tested. None of us will turn up in the COVID statistics.

But in early/mid February, there definitely was some coronavirus here -- we had a few known travel cases, and we had tons of travelers between all regions of China and all parts of CA. It is entirely possible for folks to have unknowingly brought the virus here in moderate numbers.

[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.