The true number of Americans infected with the coronavirus dwarfs any official count, according to a new survey released by the Centers for Disease Control.
The study sampled individuals in Connecticut, Louisiana, Minnesota, Missouri, the New York City metro area, Philadelphia, the San Francisco Bay Area, South Florida, Utah and western Washington State.
The study, published by the Journal of the American Medical Association, estimated that on a national basis, the real rate of coronavirus infection is about 10 times the reported rate.
As of Wednesday, about 3.9 million Americans had tested positive for the virus, according to the Johns Hopkins Coronavirus Resource Center. The death toll from the virus in the U.S. as of Wednesday was just over is 142,00, according to the center. Using those numbers and the average rate reported by the study would mean that almost 39 million Americans have had the virus.
Unlike testing for the presence of the virus, this survey tested blood samples for the presence of antibodies against it. If the body generates antibodies to fight off a virus, it is a marker that the virus was once present in the body.
“These data continue to show that the number of people who have been infected with the virus that causes COVID-19 far exceeds the number of reported cases,” said Dr. Fiona Havers, a CDC researcher who led the study, according to The New York Times.
“Many of these people likely had no symptoms or mild illness and may have had no idea that they were infected.”
It was the largest study of its kind to date, according to The Times.
The Times report noted that roughly 40 percent of those infected by the virus never develop COVID-19.
In New York City, the CDC antibody test estimated that the true number of those infected is 12 times higher than official counts in an April test, and 10 percent than counted in a May test, The Times reported.
In Missouri, the CDC estimated that the true rate of infection was 13 times the rate reported, according to The Times.
Not all states were that high. In Connecticut, for example, the rate of infection determined by the presence of antibodies was only six times higher than the rate determined by testing for the virus.
“This is not coming as a shock or surprise to epidemiologists,” Carl Bergstrom, an infectious diseases expert at the University of Washington in Seattle, told The Times. “All along, we have expected that only about 10 percent of the cases will be reported.”
“Our best estimate right now is that for every case that’s reported, there actually are 10 other infections,” Dr. Robert Redfield, director of the CDC, had said last month, according to NBC.
The fact that the vast majority of Americans infected do not know that they carry the virus means taking precautions is all the more important, Havers said.
“Many people may not realize that they’re infected, but they could still be transmitting the virus,” Havers said, according to The Associated Press.
“It’s critical that the public follows the public health recommendations like wearing cloth face coverings, remaining 6 feet apart from other people, washing hands frequently, and staying home when sick,” she said.
In its reporting, The Times said that despite the large numbers of Americans likely infected, not enough have been infected to create what is known as herd immunity. The Times said that for the virus to be largely ineffective against the general population, at least 60 percent of the population would have to be exposed to the virus.
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