Let’s look at NYC:
21% of people tested positive. That’s about 1.75 million.
The test they used is (supposedly) an IgG-only test, where detectable antibodies may take up to four weeks to develop. We could be looking at data from the middle of March — spread didn’t stop when restaurants and some stores closed, just slowed down to an R0 of about 0.8.
We could be looking at exposure rates of close to 50% at this stage. Death rates could range from 0.8% to 0.3% assuming 15000 deaths.
NY state is also very split between the NYC area – 21% exposure in the city, about 15% in the burbs, and upstate, where it’s more like 3 to 4%.
As far as the disparity between basic R0 and household attack rate, is it possible that some people have either innate (T-cell) immunity to this thing, were exposed to other coronaviruses in the past that created antibodies that can also attack SARS CoV2, or they could have a strong enough innate response to clear the virus?
