Antibody Testing Reveals CV More Widespread Than Previously Thought

Coronavirus antibody testing shows LA County outbreak is up to 55 times bigger than reported cases

Hannah Miller

Noah Higgins-Dunn

• The Covid-19 outbreak in Los Angeles County could be up to 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.
• The data, if correct, would mean that the county’s fatality rate is lower than originally thought.
• With just 4% of the population infected with the disease, LA County is still very early in the epidemic, said USC professor Neeraj Sood, who led the study.

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.

On Sunday, New York Gov. Andrew Cuomo said the U.S. Food and Drug Administration approved the state’s antibody test, and the state will conduct “thousands” of tests this week. The antibody tests will give the state its “first true snapshot” of how many people in the state have been infected with Covid-19, he said. 

“We don’t really know how many people were infected. How many people had coronavirus but self-resolved. We don’t really know because we haven’t been able to do testing on that large of scale,” Cuomo said.