Hundreds of thousands of LA County residents may have been infected with coronavirus, study finds

LOS ANGELES (KABC) -- An estimated 4.1 percent of adult residents in Los Angeles County have the antibody to the coronavirus, which indicates that hundreds of thousands of them may have been infected, according to preliminary results from a new study.

The collaborative study from USC and the county's department of public health suggests "infections from the new coronavirus are far more widespread than previously thought." The study indicates that approximately 221,000 to 442,000 adults in the county have had the infection at some point in time. The results also suggest that the mortality rate is much lower.

An estimated 4.1 percent of residents in Los Angeles County have the antibody to the coronavirus, according to preliminary results from a new USC study.

That figure is 28 to 55 times bigger than the 7,994 confirmed COVID-19 cases in the county at the time of the study in early April, according to the study. As of Monday, there are 13,816 positive cases in the region.

"These results indicate that many persons may have been unknowingly infected and at risk of transmitting the virus to others," said Dr. Barbara Ferrer, county public health director.

Some antibody tests for COVID-19 previous infection can give false results, experts say

Some antibody tests which aim to determine if a person has already been exposed to, and has recovered from, COVID-19, can give false results, experts say.

The results are part of an ongoing study in which researchers will continue to conduct antibody testing on a series of adults over the next few months to determine the presence and scope of the coronavirus across the county.

A total of 863 people in the county were tested for the first round, according to Dr. Neeraj Sood with USC, who said that we need to assume that we could be infected at any point in time, given the high rate of people that have already contracted the virus.

However, officials caution that testing positive for the antibodies does not mean a person is immune and that more research is needed.

"The concern here is we don't want the public to interpret these test results as, 'Oh, I think I have immunity,' because that question hasn't been credibly, scientifically answered yet," said Sood.

COVID-19 antibody testing: USC researchers weigh in about large-scale testing

What if you could take a peek into your body to find out if you're immune to COVID-19 and not contagious. That could be your ticket outside! That's the hope, but it may not be that simple.

Sood says even if you are antibody positive there's no knowing how much immunity to the virus you have and how long that immunity will last.

"I still sort of cringe at the thought of many, many people crowding into a small restaurant or bar." said Dr. Paul Simon of the L.A. County Department of Public Health. "At this point, I think that just sort of invites widespread viral transmissions."

There will be a second round of tests done in the near future, which the doctors say will provide further clarity.