USC and the Los Angeles County Department of Public Health announced on April 20 that antibody tests from earlier in the month show that around 4.1% of the county’s adult population has antibodies to COVID-19.
According to a press release, 1,000 people in the county were tested at six sites on April 10-11. The results suggest that the number of those infected with the virus was 28-55 times higher than nearly 8,000 cases reported earlier in the month, meaning that from 221,000-441,000 adults had contracted the virus.
Los Angeles Times reporter Soumya Karlamangla noted on Twitter that the antibody testing suggests that the COVID-19 fatality rate in the county is 0.09-0.15%.
This study suggests that the covid fatality rate in LA County, currently estimated to be around 4%, is probably more likely between .15 and .09%, when accounting for all the infections that have not been counted.
— Soumya (@skarlamangla) April 20, 2020
USC Professor Neeraj Sood, one of the study’s lead investigators, said in a statement that the results “suggest that we might have to recalibrate disease prediction models and rethink public health strategies.” County Public Health Department Chief Science Officer Dr. Paul Simon, on the other hand, 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.”
County Public Health Director Dr. Barbara Ferrer said in an April 20 press briefing that it’s unclear if those who have COVID-19 antibodies are immune to the virus.
“More research is really needed to understand what protection do people have who have already been infected with COVID-19,” she said.
Similar antibody test results in Santa Clara County and Chelsea, Mass., were released on April 17. The Santa Clara results suggest that 2.49%-4.16% of the population in the county have COVID-19 antibodies; 32% of the 200 participants in the Chelsea study tested positive for the antibodies.
As of this writing, there are 13,816 confirmed cases in Los Angeles County and 617 deaths from the virus.
