CDC says spread of COVID-19 within the US likely began in January

A new report from the U.S. Centers for Disease Control and Prevention found that the novel coronavirus has been spreading within the U.S. as early as January.It was originally reported that the first case of COVID-19 with no known connection to travel abroad happened in late February.

But the CDC said new evidence suggests “that limited U.S. community transmission likely began in late January or early February 2020, after a single importation from China, followed by multiple importations from Europe."

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The CDC added that because COVID-19 incidence was too low at the time the first cases of infection began to emerge, it was harder to detect the disease earlier. 

Analyzing data from multiple cases of coronavirus patients who died in early February indicates that “sustained, community transmission had begun before detection of the first two nontravel–related U.S. cases,” according to the CDC.

“The widespread emergence of COVID-19 throughout the United States after February highlights the importance of robust public health systems to respond rapidly to emerging infectious threats,” the CDC wrote. 

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The organization also noted two important cases of COVID-19 involving two California residents, one of which became ill on January 31 and later died on Feb. 6, and another unrelated resident who died between Feb. 13 and 17. According to the CDC, neither individual had traveled internationally in the weeks preceding their deaths. The CDC said their deaths were certified by a medical examiner as coronavirus-related. 

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FILE - A waiter wears a mask and gloves as he takes customers' orders at a restaurant in the Adams Morgan neighborhood in Washington, DC on May 29, 2020. (Photo by Drew Angerer/Getty Images)

The CDC also added that an outbreak of COVID-19 occurred during two consecutive voyages of a Grand Princess cruise ship and the health agency found evidence suggesting that an unidentified individual was infected with the virus before boarding the ship which left the Port of San Francisco on Feb. 11 for a round-trip cruise. 

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As of Feb. 20, 3,063 people on board the ship were administered tests with a total of 634 people testing positive, according to a study published on March 12 in the journal “Eurosurveillance.”

What remains unknown to researchers is the exact date of entry of the virus into the United States. The CDC links a possible early source to a Washington state resident who became ill with the virus on Jan. 19 after returning from Wuhan, China, according to the organization.