Antibody testing in New York, Los Angeles finds COVID-19 infections greatly exceed confirmed cases

Staff Writer

Preliminary results of COVID-19 antibody testing in New York state and Los Angeles County show the fatality rate is much lower than previously thought, with infections being more widespread.

New York Gov. Andrew Cuomo's "aggressive" antibody testing started earlier this week with 3,000 samples selected from 40 locations in 19 counties. The preliminary results showed nearly 14% returned positive—meaning there could be 2.7 million infections statewide—greater than 10 times the over 260,000 confirmed cases. With 16,000 deaths in New York, the mortality rate would move from as high as 6% to 0.5%, although still much higher than the 0.1% mortality rate of the seasonal flu.

The University of Southern California and Los Angeles County Department of Public Health released a smaller sample of preliminary antibody testing earlier this week, as part of its ongoing research. Based on results from 863 adults, 4.1% of the population had COVID-19 antibodies. Adjusting for margins of error to 2.8-5.6% would mean anywhere from 221,000 to 442,000 adults in LA County have been infected—28 to 55 times greater than the 7,994 confirmed cases in the area.

With the results, health officials emphasized the importance of continued testing efforts. The preliminary results from both tests show the mortality rate is significantly less and the infection rate is even greater than initially thought. Those who are elderly or have underlying health conditions still face significant risks when becoming infected.