USC Study Estimates Over 4 Percent Of Angelenos Have Contracted Coronavirus

LOS ANGELES (CBSLA) – An antibody study conducted earlier this month estimates that more than 4 percent of the Los Angeles County population has likely at some point been infected with the coronavirus, officials announced Monday.

L.A. Police Department Detective Michael Chang’s wife Dana hugs a well-wisher after Chang was released from Providence St. John’s Health Center following a long battle with coronavirus on April 17, 2020 in Santa Monica. (Getty Images)

The serology test, conducted by the L.A. County Public Health Department and USC, concluded that 4.1 percent, or 320,000 people, may have been infected with coronavirus.

“This gives us a better understanding of how much of our population been infected with the COVID-19 virus regardless of whether they were ever tested or they even had any symptoms,” L.A. County Public Health Director Dr. Barbara Ferrer told reporters Monday.

Serology testing is blood-based testing that determines whether an individual has contracted coronavirus based on the presence of antibodies in their system.

The LA County-USC serology study was conducted between April 10 and April 14 on 863 L.A. County residents.

Based on the margin of error for the study, anywhere from 221,000 to 442,000 Angelenos may have been infected with coronavirus at some point.

“So although I report that every day we have thousands of thousands of people who have tested positive, the serology testing lets us know that we have hundreds of thousands of people that have already developed antibodies to the virus; because at some point in time during the last couple of months, they have in fact been infected with COVID-19,” Ferrer said.

The study found that the number of people with coronavirus is anywhere from 22 to 55 times higher than the number of reported cases.

As of Monday, there were 13,816 confirmed cases of coronavirus in L.A. County.

USC professor Dr. Neeraj Sood, the lead investigator on the study, said Monday that the results indicate coronavirus’ mortality rate could be significantly lower than initially thought. L.A. County’s mortality rate as of Friday was 4.3 percent.

“We haven’t known the true extent of COVID-19 infections in our community because we have only tested people with symptoms, and the availability of tests has been limited,” Sood, the lead investigator on the study, said. “The estimates also suggest that we might have to recalibrate disease prediction models and rethink public health strategies.”