As flashed on LBREPORT.com's front page and Facebook platform, L.A. County Dir. of Public Health Dr. Barbara Ferrer stated at the County's April 20 daily briefing that random sample serology (blood) testing of a little over 800 L.A. County residents for COVID-19 antibodies (indicating if person has ever been positive for COVID-19 regardless of whether they tested positive or had symptoms) estimates prevalence of COVID-19 in LA County to be 4.1% (with a range that could be as low as 2.8% or as high as 5.6% when test's reliability is factored in.)
This means an estimated 221,000 adults at the low end, and as high as 442,000 at the high end appear to have been exposed to COVID-19. And this also means COVID-19 is much more prevalent than current "positive" test case numbers show. Put another way, while officials have been reporting thousands of people tested positive, the study indicates a few hundred thousand people already have antibodies to the virus because they were infected with it whether they realized it or not.
This is similar to antibody results in a study by Stanford University scientists previously reported by LBREPORT.com.

The results invite the inference that the virus is statistically less deadly than previously thought since many more people have been exposed to it than have died from it. At the same time, it shows that a far larger number of individuals harbor the virus and were or are capable of spreading it. It remains true that for reasons not currently understood, some people experience serious illness (for which there are not current therapies) and some do not survive..

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At the briefing he said "We are very early in the epidemic, and many more people in L.A. County could potentially be impacted...And as those number of infections arise, so will the number of deaths, the number of hospitalizations, and the number of ICU admissions."

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An an L.A. County Dept. of Public Health release,stated:

....The results are from the first round of an ongoing study by USC researchers and Public Health officials. They will be conducting antibody testing over time on a series of representative samples of adults to determine the scope and spread of the pandemic across the county.

Based on results of the first round of testing, the research team estimates that approximately 4.1% of the county's adult population has antibody to the virus. Adjusting this estimate for statistical margin of error implies about 2.8% to 5.6% of the county's adult population has antibody to the virus- which translates to approximately 221,000 to 442,000 adults in the county who have had the infection. That estimate is 28 to 55 times higher than the 7,994 confirmed cases of COVID-19 reported to the county by the time of the study in early April. The number of COVID-related deaths in the county has now surpassed 600.

"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," said lead investigator Neeraj Sood, a USC professor of public policy at USC Price School for Public Policy and senior fellow at USC Schaeffer Center for Health Policy and Economics. "The estimates also suggest that we might have to recalibrate disease prediction models and rethink public health strategies."

The results have important implications for public health efforts to control the local epidemic.

"These results indicate that many persons may have been unknowingly infected and at risk of transmitting the virus to others," said Dr. Barbara Ferrer, director of the L.A. County Department of Public Health. "These findings underscore the importance of expanded polymerase chain reaction (PCR) testing to diagnose those with infection so they can be isolated and quarantined, while also maintaining the broad social distancing interventions."

The antibody test is helpful for identifying past infection, but a PCR test is required to diagnose current infection.

"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 L.A. County Department of Public Health and co-lead on the study.

The study's results have not yet been peer reviewed by other scientists. The researchers plan to test new groups of participants every few weeks in coming months to gauge the pandemic's trajectory in the region.

About the study With help from medical students from the Keck School of Medicine of USC, USC researchers and Public Health officials conducted drive-through antibody testing April 10th and 11th at six sites. Participants were recruited via a proprietary database that is representative of the county population. The database is maintained by LRW Group, a market research firm.

The researchers used a rapid antibody test for the study. The FDA allows such tests for public health surveillance to gain greater clarity on actual infection rates. The test's accuracy was further assessed at a lab at Stanford University, using blood samples that were positive and negative for COVID-19.

In addition to Sood and Simon, other authors and institutions contributing to the study include Peggy Ebner of the Keck School; Daniel Eichner of the Sports Medicine Research & Testing Laboratory; Jeffrey Reynolds of LRW Group; Eran Bendavid and Jay Bhattacharya of Stanford University School of Medicine.

The study was supported with funding from USC Schwarzenegger Institute, USC Lusk Center, USC President's Office, Jedel Foundation, LRW Group, Soap Box Sample, and several individual donors.

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