Los Angeles County COVID-19 Antibody Testing Finds Prevalence Rate At Least 28 Times Higher Than Confirmed Cases

About 4.1% of the population in Los Angeles County, California, had already had coronavirus disease 2019 (COVID-19) as of April 20, 2020, based on the preliminary results of a study that tested 863 adults for antibodies to COVID-19. These results are from the first round of an ongoing study by researchers at the University of Southern California and county public health officials.

As of early April 2020, 7,994 confirmed cases of COVID-19 had been reported to the county, with more than 600 COVID-19-related deaths. However, based on the rate of positive tests within . . .