LA Public Health just released early results from their antibody testing suggesting that between 2.8% and 5.6% of the population has been infected. With 619 deaths, this implies a fatality rate between 0.41% and 0.28%.
The influenza death rate is often quoted as 0.1%, but that comes from dividing the number of flu deaths (34 thousand in 2018-2019) by the count “symptomatic illnesses” (35 million in 2018-2019) (reference). The death rate for flu is lower if you include non-symptomatic illnesses to make the results comparable to the antibody analysis.
If we assume the 0.35% fatality rate applies everywhere, we can estimate the percent infected in any region. For example, New York City has 14,604 deaths implying 14,604/0.35% = 4.2 million infections. With 8.4 million inhabitants, this implies 50% of New Yorkers have already been infected. This does not give the virus much room to grow there. I hope we can get an antibody survey in New York to check this.
Santa Clara County has 83 deaths implying 83/0.35% = 24 thousand infections. With 2 million inhabitants, this implies 1.2% have been infected. This is not too far from antibody results released a few days ago that estimated 2-4% of Santa Clarans have been infected.