People wear their face masks waiting in line for an emergency food distribution at the 88th Street Temple Church of God in Christ on April 14, 2020 in Los Angeles, California, during the coronavirus pandemic.

The Covid-19 outbreak in Los Angeles County is likely far more widespread than previously thought, up to an estimated 55 times bigger than the number of confirmed cases, according to new research from the University of Southern California and the LA Department of Public Health.

USC and the health department released preliminary study results that found that an estimated 4.1% of the county's adult population has antibodies to the coronavirus, estimating that between 221,000 adults to 442,000 adults in the county have had the infection.

This new estimate is 28 to 55 times higher than the 7,994 confirmed cases of Covid-19 reported to the county through early April. The number of coronavirus-related deaths in the county has now surpassed 600, according to the Department of Public Health. The data, if correct, would mean that the county's fatality rate is lower than originally thought.

The results are based on antibody testing of about 863 people who were representative of LA County, the researchers said.

"Though the results indicate a lower risk of death among those with infection than was previously thought, the number of Covid-related deaths each day continues to mount, highlighting the need for continued vigorous prevention and control efforts," said Dr. Paul Simon, chief science officer at the LA County Department of Public Health and co-lead on the study, in a statement.