Los Angeles study suggests coronavirus much more widespread

LOS ANGELES — An estimated 320,000 adults in Los Angeles County may have been infected with coronavirus, according to preliminary results of a study that suggests the illness is far more widespread than current testing shows and the death rate is much lower.

The study conducted April 10-14 by the county and the University of Southern California estimated that approximately 4.1% of the county’s adult population of 8 million has antibodies to the virus. When adjusted for margin of error, the infection rate ranged from 2.8% to 5.6%, or about 220,000 to 440,000 adults.

The study follows other research that has suggested more people have had coronavirus without symptoms — or without feeling bad enough to seek a test. But it also means that more people have been silent carriers of the virus that has killed nearly 1,200 people in California.

“Given the high rate of people that may have been infected at some point with COVID-19, we need to assume that at any point in time that we could be infected and that all the other people that we come in contact with could also be infected,” Public Health Director Barbara Ferrer said.

Until the study was announced, the county has been relying on testing people who are sick or have symptoms of the virus to determine the rate of people with infection and the per cent of people who have died. But that statistic is biased because only a limited number of people can get the test and many people are believed to be asymptomatic or could have symptoms consistent with the flu or colds also prevalent this time of year.

At the time the testing was conducted, the county reported nearly 8,000 cases, meaning that the actual number was probably 28 to 55 times higher and the fatality rate was much lower than that based on the number of people tested.

“The fatality rate is not the only number we should focus on,” said Neeraj Sood, a USC professor of public policy. “What the findings show is that only 4% of our population has been infected, which means we are very early on in the epidemic and many more people in LA County could potentially be infected. And as those number of infections rise, so will the number of deaths, the number of hospitalizations and the number of ICU admissions.”

As of Monday, the county had 13,816 cases out of 80,000 people tested, or 13% positive. The county had more than 600 deaths, which accounts for about half the state’s total. The county has 10 million residents, or a quarter of the state’s population.

California had over 32,000 reported cases Monday and 1,181 deaths, according to Johns Hopkins University.

Brian Melley, The Associated Press