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Coronavirus cases may have been spreading in Wuhan and Seattle weeks before first detected: researchers

Coronavirus cases may have been spreading in Wuhan and Seattle weeks before first detected: researchers
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Thousands of cases of the novel coronavirus may have circulated undetected in both Wuhan, China, and Seattle early in the pandemic, according to research from the University of Texas-Austin published in The Lancet.

The research suggests that by the time lockdowns were imposed in both cities, the early epicenters of their respective countries, the virus may have been spreading for weeks.

Researchers analyzed data from two separate studies that retested samples from patients with flu-like symptoms in January in Wuhan and in February and March in Seattle.

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They determined the ratio of coronavirus-positive swabs to flu-positive swabs and compared this to Washington state and China surveillance data on flu cases.

The results indicated there could have been more than 12,000 undetected but symptomatic cases in Wuhan by the time the city locked down on Jan. 23. In the meantime, by the time Seattle closed schools on March 9, there were likely more than 9,000 undetected cases, one-third of them children.

Specifically, they concluded that there were two undetected coronavirus cases in Wuhan for every three cases of flu in adults, indicating it was likely spreading through the city as early as mid-November 2019.

In Seattle, meanwhile, the ratio estimate was one undetected case for every nine flu cases in children. The ratio was 1 to 7 in adults. On March 9, when the city had 245 recorded cases of the virus, data suggest there could have been up to 9,000 symptomatic cases.

“As the virus started spreading in cities across the United States and cities across the world, probably by the time we started detecting cases, it’s likely that the virus had been spreading for several weeks, if not months,” Lauren Ancel Meyers, a professor of integrative biology and statistics and data sciences, told the Houston Chronicle.