Results of the joint USC-Los Angeles County COVID-19 antibody test study were released Monday afternoon with results suggesting that the number of adults infected with the virus may be 55 times higher than the number of reported cases in the county. This study also suggests that the mortality rate of COVID-19 in Los Angeles County may be as low as 0.1% to 0.2%.
The study was conducted from April 10 to 14, when 863 LA County residents were tested for the presence of antibodies in their system. Of those tested, 4.1% returned a positive test, although the true range of positive results is likely between 2.8% to 5.6% due to the possibility of false-negative or false-positive results. These numbers suggest that anywhere between 221,000 and 442,000 adults may have been infected, whereas the number of reported positive cases in LA County was 7,994 at the time of the study, according to the Los Angeles County of Public Health. The study’s results have not yet been peer-reviewed by other scientists.
Dr. Paul Simon, chief science officer at L.A. County Department of Public Health and co-lead on the study, noted that though the projected mortality rate may be much lower in LA County than around the country and abroad, the virus still poses a threat to residents. Dr. Simon said, if the current rate of infection continues, COVID-19 could become the leading cause of death in Los Angeles County.
Dr. Simon noted that it is “unclear how much protection having the antibodies gives someone,” and that more research needs to be conducted to find out. Simon suggested that even those whose antibody test came back positive should continue to follow the social distancing measures set forth by public health officials.
Dr. Neeraj Sood is a professor at the USC Price School for Public Policy, senior fellow at USC Schaeffer Center for Health Policy and Economics and co-lead on the study. He stated that more information is needed to reach a definitive conclusion, which means more testing is needed. Dr. Sood wants to collect more data in order to track the epidemic and get more accurate information, which could in turn be used to help models predict when social distancing measures can safely be relaxed.
Results also indicate that there may be a gender and age bias for the virus, and seem to suggest that minority communities are more likely to be exposed to the virus. African Americans tested positive at the highest rate of 7%, while those aged 35 to 54 tested positive at the highest rate of 5.6%. Additionally, men tested positive at a slightly higher rate than women. However, Dr. Simon and Dr. Neeraj Sood cautioned that the results of this study are preliminary and more testing needs to be done to confirm if these trends are accurate on a larger scale.
Among the other goals for future rounds of testing, Dr. Sood and Dr. Simon stated that they want to offer more in-home testing, increase representation among participants in the study and release test surveys in multiple languages. The next round of testing will take place in two to three weeks.