A new analysis of blood samples from 24,000 Americans taken early last year is the latest and largest study to suggest that the new coronavirus popped up in the U.S. in December 2019 — weeks before cases were first recognized by health officials.
While the analysis is not definitive, and some experts do remain skeptical, federal health officials are inclined to accept a timeline that suggests the SArS-COV-2 virus was in the United States in December 2019, weeks before it was first detected.
Scientists analyzing 24,000 blood samples taken for a National Institutes of Health research program called All of Us, identified nine people in states from Mississippi to Wisconsin to Pennsylvania who were infected days or even weeks before the first cases in their states were identified.
Their findings were published online by the journal Clinical Infectious Diseases Tuesday. “The studies are pretty consistent,” said Natalie Thornburg of the Centers for Disease Control and Prevention (CDC).
Background on the SARS-COV-2 virus
The coronavirus emerged in China’s Wuhan Province in late 2019. The first case in the United States was identified in a traveler from Washington state who returned home on January 15, after a trip to Wuhan. He became ill and sought help at a clinic on January 19, 2020.
CDC officials have said the spark that started the spread of the virus in the U.S. arrived during a three-week window from mid-January to early February. However, later research and studies have suggested the virus was in this country earlier than health officials thought.
As the researchers note in their paper, there was limited testing for the virus at the start of the pandemic, a period encompassing January through March. At that time, testing was focused on symptomatic patients with a travel history.
This, in turn, obscured the picture of SARS-CoV-2 seeding and community transmission. So the researchers sought to identify individuals with SARS-CoV-2 antibodies in the early weeks of the US epidemic.
A CDC-led study published in December 2020 that analyzed 7,000 samples from American Red Cross blood donations suggested the coronavirus infected some Americans as early as the middle of December 2019.
In the current study, as was done in the earlier CDC study, researchers looked for antibodies in the blood that are taken as evidence of coronavirus infection and can be detected as early as two weeks after a person is first infected.
Specif9cally, the researchers say that nine people – five from Illinois, and one each from Massachusetts, Mississippi, Pennsylvania, and Wisconsin – were infected earlier than any COVID-19 case was ever reported in those states.
“While it is entirely plausible that the virus was introduced into the United States much earlier than is usually appreciated, it does not mean that this is necessarily strong enough evidence to change how we’re thinking about this,” said William Hanage, a Harvard University expert on disease dynamics.
The NIH scientists have yet to follow up with any of the participants in the study and have not verified if the nine people had traveled out of the country during that critical period. It will be interesting to have that information.
