Finally, we are getting some good statistics.   A very interesting study of total COVID infection rate has made its rounds through the news.   The methods appear reasonable and the conclusions are interesting in that infections in that county are 50 to 85 times more cases of infection than our reported.

COVID – 19 Antibody Seroprevalence in Santa Clara County, California

This data leads the authors to the conclusion that the virus is much less deadly than we’ve been led to believe.

A hundred deaths out of 48,000 – 81,000 infections corresponds to an infection fatality rate of 0.12 – 0.2%.

What’s very nice about this paper is that it is statistically simplistic making it easy for most to understand.

At StatNews site, an article I read some time ago reported similar results based on DiamondPrincess data.
Projecting the Diamond Princess mortality rate onto the age structure of the U.S. population, the death rate among people infected with Covid-19 would be 0.125%. But since this estimate is based on extremely thin data — there were just seven deaths among the 700 infected passengers and crew — the real death rate could stretch from five times lower (0.025%) to five times higher (0.625%).
For perspective, the common flu which is much better studied than a new virus has a mortality rate of about 0.08%.   Still, if we assume the us statistics were even 50 times more infections, somewhere around 3 million people are walking around with the virus antibodies already completely unaware of their problem, and we would have approximately a 0.1% death rate for those who have been exposed to the virus.  Several more of these studies will be out soon, the data should be very interesting.