The true number of Americans who've been infected with COVID-19 may top 20 million, according to new estimates from the Centers for Disease Control and Prevention.
"Our best estimate right now is that for every case that's reported, there actually are 10 other infections," CDC director Dr. Robert Redfield said on a call with reporters Thursday.
The estimate comes from looking at blood samples across the country for the presence of antibodies to the virus. For every confirmed case of COVID-19, 10 more people had antibodies, Redfield said.
Currently, there are 2.3 million COVID-19 cases reported in the U.S. The CDC's new estimate pushes the actual number of coronavirus cases up to at least 23 million.
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"This virus causes so much asymptomatic infection," Redfield said. "The traditional approach of looking for symptomatic illness and diagnosing it obviously underestimates the total amount of infections."
The estimation comes amid rises in cases across the Southeast and Western U.S.
He urged Americans to be vigilant about behavior measures known to minimize spread of the coronavirus.
"The most powerful tool that we have is social distancing," Redfield said. That means maintaining a physical distance of at least six feet in public, wearing face coverings and ongoing hand-washing.
"If you must go out into the community, being in contact with fewer people is better than many," Redfield added.