Great question. Answer: Still looking. Here are a couple of pieces that 'hint' at this: https://thehill.com/policy/healthcare/499085-cdc-acknowledges-mixing-up-coronavirus-testing-data  The Centers for Disease Control and Prevention (CDC) acknowledged Thursday that it is combining the results from viral and antibody COVID-19 tests when reporting the country's testing totals, despite marked differences between the tests.  https://reason.com/2020/06/28/cdc-antibody-studies-confirm-huge-gap-between-covid-19-infections-and-known-cases/  Newly published antibody test results from half a dozen parts of the country confirm that COVID-19 infections in the United States far outnumber confirmed cases. The ratio of estimated infections to known cases in these studies, which the U.S. Centers for Disease Control and Prevention (CDC) reported on Friday, range from 6 to 1 in Connecticut as of early May to 24 to 1 in Missouri as of late April.