The coronavirus outbreak in Los Angeles County could be up to 55 times more widespread than previously thought with a much lower fatality rate, according to a new study.

The University of Southern California and the Los Angeles Department of Public Health released research Monday that found 4.1% of adults in the county had antibodies to the coronavirus and estimated between approximately 221,000 to 442,000 adults have already had the virus. The county, home to more than 10 million people, had confirmed just 13,816 cases as of Monday.