What if COVID actually arrived in the US far earlier than we currently think?

The timeline of COVID-19's arrival in the United States is a murky piece of history, but recent investigations and revelations may provide a crucial piece in the pandemic puzzle.

According to the current historical outline, the virus was originally reported as a cluster of cases in Wuhan, China, on Dec. 31, 2019. Two weeks later, a case was recorded in Thailand. One week after that, on or about Jan. 20, 2020 (the records of various official sources differ slightly on the exact day), the first case was confirmed in the U.S.

Researchers from the Centers for Disease Control and Prevention (CDC) published a study earlier this month that revealed the findings of an investigation of thousands of blood donation samples collected by the Red Cross between Dec. 13, 2019, and Jan. 19, 2020.

The CDC's conclusion suggests that our current timeline may not be so accurate.

In this Dec. 8, 2020, file photo, a healthcare worker wears personal protective equipment as she speaks to a patient at a mobile testing location for COVID-19 in Auburn, Maine. (AP Photo/Robert F. Bukaty, File)

Of the more than 7,300 blood donation samples tested by the CDC, 106 specimens showed evidence of coronavirus antibodies. From those 106, a group of 84 samples that underwent further testing possessed the specific protein structure needed to block SARS-CoV-2, the virus that causes COVID-19, from entering cells.

Dr. Natalie Thornburg, a respiratory viruses immunologist and one of the researchers involved with the study, told AccuWeather that while they can't be 100% certain that all the antibodies are a result of SARS-CoV-2, their extensive testing makes that "very likely."

"In that original manuscript we did find one that had a very, very, very high signal, and blocked the piece of the protein from the virus from binding the cell protein at a very high percentage. It also blocked virus entry into the cells, so that one is very likely from a SARS-2 infection," Thornburg said, referring to one of the antibodies in the sample. "I believe there was another one that also was positive, that one may be likely as well. But even with the 84, we are not able to say with 100% certainty they are all from SARS-2 infections."

Despite the absence of certainty, the overwhelming evidence pushed the researchers to conclude that their data does indeed "suggest that SARS-CoV-2 may have been introduced into the United States prior to January 19, 2020."

This 2020 electron microscope image made available by the U.S. Centers for Disease Control and Prevention shows the spherical particles of the new coronavirus, colorized blue, from the first U.S. case of COVID-19. Antibody blood tests for the coronavirus could play a key role in deciding whether millions of Americans can safely return to work and school. But public health officials warn that the current "Wild West" of unregulated tests is creating confusion that could ultimately slow the path to recovery. (Hannah A. Bullock, Azaibi Tamin/CDC via AP)

The results were both surprising and not surprising, Thornburg said. While she said the uncovering of positive antibodies wasn't shocking, the number of blood samples with such antibodies and the areas in which they came from were a surprise.

The blood samples came from donors in nine states: California, Connecticut, Iowa, Massachusetts, Michigan, Oregon, Rhode Island, Washington and Wisconsin. From those states, Thornburg was particularly surprised by the cluster coming from Northern California.

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"I was surprised by the number from Northern California in December. I think it was like 2.6% from Northern California in December," Thornburg said. "That's not to say that there were 2.6% of people from California who had the infection, this is not a representative sample and you can't extrapolate a number of the specimens we saw to the general population, but I was surprised by that number," she said. "And I was surprised by the number we saw the neutralizing, the 84."

Thornburg said that the positives weren't surprising because of how quickly the positive infections were confirmed in January once officials began looking. The turnaround between the start of CDC testing on Jan. 18 and the first patient being identified days later shows that the virus had established prevalence in the country at that point, she said.

A health worker organizes coronavirus antibody test results at an office in Bali, Indonesia on Friday, Sept. 11, 2020. (AP Photo/Firdia Lisnawati)

If that initial confirmed infection on Jan. 20 truly was the first American patient, "It would've been like [finding] a needle in a haystack," she said.

The recently published data gives epidemiologists some more potential clarity, but it also raises a number of other questions: Namely, why didn't we see the high rates of transmission in December and January that we later saw in March and April?

Hong Kong University pathology professor John Nicholls raised that query in an email with AccuWeather and further suggested that more analysis of those Red Cross blood donors would need to be completed in order to better understand the findings.

"CDC is normally very robust in their methodology, but from a clinical point of view, if the virus was circulating before, given what we know about the infectiousness of the virus, why did these mystery patients not show any clinical symptoms, or transmit to other people, or lead to further outbreaks?" Nicholls wondered in his email.

In this Sunday, Jan. 26, 2020 file photo, Gao Fu, foreground left, the head of the Chinese Center for Disease Control and Prevention, speaks to journalists after a news conference about a virus outbreak at the State Council Information Office in Beijing. On Dec. 31, 2019, Gao dispatched a team of experts to Wuhan. Also on Dec. 31, the World Health Organization first learned about the cases from an open-source platform that scouts for intelligence on outbreaks, emergencies chief Michael Ryan has said. (AP Photo/Mark Schiefelbein)

Dr. George Rutherford, professor of epidemiology and biostatistics at the University of California, San Francisco, raised similar questions in an exclusive interview with AccuWeather. Regarding the results of the study, he said he viewed the data "as a lab artifact" and said it was hard to believe the findings of studies that push the timeline back too far.

"I think that I could give you early January or maybe late December, but we would have seen lots and lots and lots of disease and lots of mortality that would not have escaped detection," he said.

If given the opportunity to learn more about the publication's data, Rutherford said that he would most like to understand more about the donors' travel histories and geographic information.

"It'd be very compelling if it turned out to be a bunch of positive cases of 35-year-old Asian-American businessmen who go back and forth from China all the time," Rutherford said. "Then that becomes a believable story. But if it's an 80-year-old grandmother living in Des Moines, Iowa, with no contact at all, then that's a much tougher sell."

In this Feb. 29, 2020 file photo, President Donald Trump, accompanied by, from left, National Institute for Allergy and Infectious Diseases Director Dr. Anthony Fauci, Vice President Mike Pence, and Robert Redfield, director of the Centers for Disease Control and Prevention, reacts to a question during a news conference on the coronavirus in the press briefing room at the White House in Washington. Public health officials were already warning Americans about the need to prepare for the coronavirus threat in early February when President Donald Trump called it "deadly stuff" in a private conversation that has only now has come to light. (AP Photo/Andrew Harnik, File)

Dr. Bryan Lewis of the University of Virginia's Biocomplexity Institute told AccuWeather that he believes the CDC findings paint a grimmer picture of the pandemic than what is officially known. "What we're looking at now is a vast underestimate in terms of the total number of people we've lost," Lewis, who early on warned that the coronavirus could unleash widespread dire consequences, said. "I think that the impact of this has not been fully appreciated."

Regarding the transmission, or lack thereof, of those early December coronavirus patients, Thornburg said it isn't abundantly clear why higher transmission rates weren't occurring. She postulated that the infected individuals may not have attended super spreader events or engaged in close contact with large crowds of people, but without more information about the patients, that remains unclear.

With vaccines now being distributed across the country, more than 18 million cases and nearly 320,000 fatalities later, Thornburg said she is hoping her team's discoveries spur other researchers to reanalyze their specimens to continue piecing together a timeline that would go on to reshape the entire national understanding of how the pandemic unfolded.

"It's one piece to the puzzle," Thornburg said. "I hope other scientists, if they have things in their freezer they can look at and have different ways of looking at it, I hope they can go into their freezers and look at samples to see if they have some other pieces of the puzzle that can sort of fill out the picture."

Additional reporting by Bill Wadell.

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