The infection and spread of COVID-19 across the United States could be far greater if results from a new Stanford University study prove true.
The study is very preliminary -- and its results must be peer-reviewed as other studies also tackle the problem -- but the results are quite alarming.
The study used an antibody blood test to estimate how many people had been infected the the coronavirus in the past. Other tests using nasal swabs or saliva test for the virus' genetic material, which does not persist long after recovery, as antibodies do.
"We found that there are many, many unidentified cases of people having Covid infection that were never identified with it with a virus test," Dr. Jay Bhattacharya, a professor of medicine at Stanford University and one of the paper's authors, told CNN. "It's consistent with findings from around the world that this disease, this epidemic is further along than we thought."
Simply put, Stanford's study estimates that 2.49% to 4.16% of people in Santa Clara Country had been infected with Covid-19 by April 1. This represents between 48,000 and 81,000 people, which is 50 to 85 times what county officials recorded by that date: 956 confirmed cases.
Similar efforts to estimate local antibody prevalence have launched in places like Miami-Dade County, Florida; San Miguel County, Colorado; and Los Angeles, California. The National Institutes of Health has a similar effort underway as well.
If proven to be accurate, the results could mean that the upper limit of the coronavirus's mortality rate was only 0.2 percent, much lower than the nationwide death rate of 4.1 percent.
Dr. Eran Bendavid, who led the study, told ABC News that around 95 percent of the Santa Clara population were still without antibodies.
That means it would be tough to decide whether to ease restrictions because "knowing that well upwards of 90 percent of the population doesn't have antibodies is going to make that a very difficult choice."
Widespread antibody tests are instrumental in helping governments decide whether to return populations to work because those tests can help figure out who is less at risk, experts say.