The novel coronavirus appears to have been circulating in the United States last December—about one month before U.S. officials reported the country's first case of the virus, according to a CDC study published Monday in the journal Clinical Infectious Diseases.
America's surging epidemic
The study comes as U.S. officials on Monday reported about 167,759 new cases of the novel coronavirus, according to data compiled by the New York Times. As of Tuesday morning, U.S. officials had reported a total of about 13.6 million cases of the novel coronavirus since America's epidemic began—up from about 13.4 million cases reported as of Monday morning.
According to the Times, the United States' average daily number of newly reported coronavirus cases over the past week was 160,387—which is up by 3% when compared with the average from two weeks ago.
As of Tuesday morning, data from the Times showed that the rates of newly reported coronavirus cases were "staying high" in Puerto Rico; Washington, D.C.; and 36 states that have had a daily average of at least 15 newly reported cases per 100,000 people over the past week. Those states are Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Indiana, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Virginia, Washington, and West Virginia.
The Times' data also showed that, as of Tuesday morning, the daily average of newly reported cases over the past seven days was "going down" in Guam and 11 states that had been seeing comparatively higher rates of coronavirus transmission. Those states are Illinois, Iowa, Kansas, Missouri, Montana, Nebraska, North Dakota, South Dakota, Utah, Wisconsin, and Wyoming.
The U.S. Virgin Islands has had comparatively low case rates, but it was seeing those rates "going up" as of Tuesday morning, according to the Times. In Hawaii, Maine, and Vermont, meanwhile, rates of newly reported coronavirus cases were "staying low" as of Tuesday morning, according to the Times' analysis.
On Monday, U.S. officials also reported about 1,265 new deaths tied to the novel coronavirus. As of Tuesday morning, U.S. officials had reported a total of about 268,023 U.S. deaths linked to the virus since the country's epidemic began—up from about 266,758 deaths reported as of Monday morning.
Meanwhile, hospitalizations for Covid-19, the disease caused by the novel coronavirus, surged to a new high. As of Monday, 96,039 Americans with Covid-19 were hospitalized for treatment, according to data from The Atlantic's COVID Tracking Project.
Novel coronavirus likely began circulating in the US in December, CDC finds
In January, CDC reported what was believed to be the first coronavirus case in the United States. According to Axios' "Vitals," public health officials confirmed that case on Jan. 19.
However, CDC in the study published Monday said data from recent serologic testing suggests the novel coronavirus had been circulating in the United States in mid-December—weeks earlier than scientists and public health officials previously thought.
For the study, CDC researchers analyzed 7,389 samples from blood donations collected by the American Red Cross from residents in nine states—California, Connecticut, Iowa, Massachusetts, Michigan, Oregon, Rhode Island, Washington, and Wisconsin—between Dec. 13, 2019, and Jan. 17, 2020. The researchers tested the blood samples for coronavirus antibodies, which can indicate whether a person had been exposed to the virus.
The researchers found evidence of coronavirus antibodies in 106 of the 7,389 blood samples. According to the researchers, 39 of the blood samples with evidence of coronavirus antibodies had been collected in California, Oregon, and Washington between Dec. 13 and Dec. 16 of 2019, which suggests that isolated cases of coronavirus infection occurred in those in mid-December—weeks before public health officials confirmed what had been believed to be the United States' first case of the virus, which occurred in Washington.
The researchers also found that 67 of the blood samples with evidence of coronavirus antibodies had been collected in Connecticut, Iowa, Massachusetts, Michigan, Rhode Island, and Wisconsin between Dec. 30, 2019, and Jan. 17, 2020. According to the researchers, those findings indicate that coronavirus cases had become more dispersed, but remained isolated, during the beginning of this year.
When the researchers conducted further testing on 90 of the 106 blood samples that contained evidence of coronavirus antibodies, they found that 84 of the 90 samples had antibodies specific to the novel coronavirus. According to the researchers, those findings confirm that the antibodies they detected had developed to fight the novel coronavirus—and not other coronaviruses, the Wall Street Journal reports.
The researchers concluded that novel coronavirus infections "may have been present in the [United States] in December 2019, earlier than previously recognized." However, the researchers added that there likely wasn't widespread community transmission of the novel coronavirus until late February.
Overall, the researchers said their findings show the value of routinely screening collected blood samples for evidence of circulating viruses and will help public health officials broaden their understanding of the novel coronavirus (Diaz, NPR, 12/1; McKay, Wall Street Journal, 11/30; Owens, "Vitals," Axios, 12/1; New York Times, 12/1; "The COVID Tracking Project," The Atlantic, accessed 12/1).