On May 19, 2020, a University of Southern California (USC) study reported results from the first phase of a COVID-19 antibody study in Los Angeles County have been published in JAMA, the Journal of the American Medical Association.

After testing a community sample of residents for antibodies to the new coronavirus, researchers with USC and the Los Angeles County Department of Public Health calculated that many more individuals in L.A. County had SARS-CoV-2 antibodies – a sign of a past infection – than previously thought.