Results of an antibody study in Los Angeles County indicate that there have been hundreds of thousands more COVID-19 cases in the county than the amount reflected in the official statistics, which would mean the mortality rate is much lower than previously thought, according to KCOP-TV.

What did they find? Researchers from the University of Southern California conducted antibody tests on a random sample of 863 Los Angeles County residents on April 10 and 11.



They found that, based on that sample, an estimated 4.1% of the county's adult population has COVID-19 antibodies, meaning they have been infected with the virus in the past, and they potentially have some immunity to it now. Those who had the disease caused by the novel coronavirus from China may not have felt any symptoms.

When accounting for the margin of error, the results mean between 221,000 and 442,000 adults in Los Angeles County have had COVID-19. According to the Los Angeles County health department website, there were 13,816 confirmed cases in the county as of Monday.

LA County has reported 617 deaths, resulting in a 4.4% case fatality rate (number of deaths/number of lab-confirmed cases). If the USC serology study data is accurate, the true mortality rate (number of deaths/number of actual infections) would be between 0.14% and 0.28%.

Implications: Antibody studies are being conducted all over the world, and the results continue to indicate that countries are only catching a small percentage of the actual number of COVID-19 cases. In the United States, limited testing capacity means only the sickest patients typically get tested.

Interpretations of the available data have significant policy implications. Some, such as LA County's public health director Dr. Barbara Ferrer, interpret antibody test results like those from USC to mean the lockdowns should remain in place longer, because there are potentially so many asymptomatic people who are capable of transmitting the virus to others. She emphasized the need for more ability to test for COVID-19 so infected people can be aware of their condition and isolate themselves.

Still others believe that if the COVID-19 mortality rate is potentially 0.1%-0.2%, restrictions should only target people who are at high risk of COVID-19 complications due to age or underlying health problems.

At-risk people could continue isolating or social distancing, while people at low risk could resume normal activity, while the inevitable spread of the virus through that population can contribute to the development of herd immunity.

By continuing to shelter the entire population, some argue, we are only delaying the inevitable spread because the population isn't developing any immunity. A COVID-19 vaccine is at least a year away, and even then there's no guarantee that a vaccine will be successfully developed.