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New discoveries shift coronavirus timeline by months

The coronavirus that has exploded into a pandemic has almost certainly been circulating for several months longer than public health experts first suspected, masked by asymptomatic cases or illnesses incorrectly diagnosed.

Scientists believe the first known case of a patient contracting the coronavirus happened in mid-November, in a 55-year-old resident of China's Hubei province. That was six weeks before the World Health Organization's (WHO) surveillance network picked up reports of a cluster of atypical pneumonia cases in Wuhan, the province's largest city.

There are increasing signs that the virus had begun its global spread long before it was identified. French scientists on Monday published the results of a study that found coronavirus present in samples given by a resident of a Paris suburb who was tested Dec. 27, four days before the Wuhan cluster was identified.

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The French patient, a 42-year-old fishmonger, had not traveled outside of the country since visiting his native Algeria in August, a potential sign that the virus came to France in someone else even earlier. One of the man's children had symptoms of a flu-like illness, raising the prospect that the child infected the father — and further back-dating the point at which the virus had spread to Europe.

The coronavirus also likely landed in the United States earlier than the first known American case, a man north of Seattle who traveled home from Wuhan in mid-January.

Medical officials in California’s Santa Clara County said last month that a woman who died at her home on Feb. 6 had the coronavirus. That woman had not traveled recently, suggesting she contracted the virus through contact with someone else who may have returned to the Bay Area from overseas.

 Such back-dating is not uncommon when scientists are racing to identify the spread of a disease, experts said.

 "Exponential spread in the early phases is not recognized, and the reason it's not recognized is that it doesn't always cause a disease like Ebola or severe pneumonia," said Paul Sax, clinical director of the division of infectious diseases at Brigham and Women's Hospital in Boston. "This virus may have been circulating before we knew."

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Tracing a virus to its root cause, or index case, gives scientists a window into how the virus made its zoonotic leap from a host animal to humans — and helps inform changes to society and culture that can prevent future leaps.

It is not clear if the 55-year-old Hubei resident was the index case, or if others contracted the disease earlier. But its spread outside of Wuhan, a major manufacturing and transit hub, almost certainly happened long before the pathogen was even identified as a novel coronavirus, let alone before countries like the United States imposed travel restrictions to stop its spread.

"It wouldn't surprise me if it was here in December. There was so much connection between Wuhan and here, I'd be surprised if it wasn't," said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. "The horse was long out of the barn before anybody thought to close the barn door."

In some cases, a patient zero can never be identified. The AIDS epidemic of the early 1980s was not the first time HIV infected a human, Sax said, pointing to cases of what was almost certainly HIV as far back as the 1950s.

In others, contact tracers can find the person who first contracted a deadly disease. Epidemiologists from the WHO and Guinea's ministry of health traced the worst Ebola outbreak in modern history from a nurse who died in mid-January 2014 back to a toddler in the remote village of Meliandou who died in December 2013.

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What makes this particular coronavirus so difficult to detect, experts say, is that many of its symptoms manifest as nothing more than a common cold — and that the list of symptoms one might experience vary from something as simple as a runny nose to far more extreme cases that resemble heart attacks or cause strokes. The fact that the virus likely broke out just as flu season began in the Northern Hemisphere has added a layer of fog, complicating the search.

The WHO is keeping tabs on the new research, a spokesman said, and it is likely other countries will find earlier initial cases as they retest samples taken in late 2019, like the French study.

"This finding helps to better understand potential virus circulation of COVID-19. The finding is not surprising given the earliest cases of COVID-19 had symptom onset in early December. It is possible that some infected people traveled from Wuhan to other countries at that time. It is also possible that more early cases will be found as countries retest samples from patients who were sick in December-January or earlier," said Tarik Jasarevic, the WHO spokesman.

To better understand how the virus moved from China to France, scientists will need to build a "phylogenetic tree," said Joseph Eisenberg, an epidemiologist at the University of Michigan. That process involves sequencing the French sample's RNA and comparing it to strains found in China, Italy and elsewhere to see how closely it is related. So far, scientists have sequenced RNA from more than 15,000 samples to chart its spread around the globe.

International governments, led by the Trump administration and Australia, have been critical of China's efforts to silence doctors who raised alarms about the early coronavirus cases. One doctor in Wuhan alerted national health authorities that a novel coronavirus was spreading in his hospital on Dec. 27, four days before the WHO picked up hints about the cluster of pneumonia. Internal documents show as many as 60 people a day were being infected in Wuhan by Dec. 20.

But it is likely that the virus was spreading long before Chinese officials got the first indications of a new pathogen in their midst.

"If Wuhan was the location where the virus spilled over from animals to humans, there was likely lots of transmission prior to the initial identified cluster," Eisenberg said.