Early spread of COVID-19 appears far greater than initially reported

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Patients with undiagnosed flu signs who really had COVID-19 final winter had been amongst 1000’s of undetected early instances of the illness at first of this 12 months. In a brand new paper in The Lancet’s open-access journal EClinicalMedicine, epidemiological researchers from The University of Texas at Austin estimated COVID-19 to be far extra widespread in Wuhan, China, and Seattle, Washington, weeks forward of lockdown measures in every metropolis.

In the U.S., a couple of third of the estimated undiagnosed instances had been amongst kids. The researchers additionally concluded that the primary case of COVID-19 in Seattle could have arrived as far again as Christmas or New Year’s Day.

Lauren Ancel Meyers, a professor of integrative biology and statistics and information sciences who leads the UT Austin COVID-19 Modeling Consortium, labored together with her workforce of researchers to extrapolate the extent of the COVID-19 epidemic in Wuhan and Seattle based mostly on retested throat swabs taken from sufferers who had been affected by influenza-like diseases throughout January in Wuhan and through late February and early March in Seattle. When the samples had been analyzed later in every metropolis, most turned out to be flu, however some turned out to be constructive for SARS-CoV-2, the virus that causes COVID-19.

“Even before we realized that COVID-19 was spreading, the data imply that there was at least one case of COVID-19 for every two cases of flu,” Meyers mentioned. “Since we knew how widespread flu was at that time, we could reasonably determine the prevalence of COVID-19.”

When the Chinese authorities locked down Wuhan on Jan. 22, there have been 422 identified instances. But, extrapolating the throat-swab information throughout the town utilizing a brand new epidemiological mannequin, Meyers and her workforce discovered that there might have been extra than 12,000 undetected symptomatic instances of COVID-19. On March 9, the week when Seattle faculties closed as a result of virus, researchers estimate that extra than 9,000 individuals with flu-like signs had COVID-19 and that a couple of third of that complete had been kids. The information don’t indicate that had been conscious of these infections, quite that they could have gone unseen in the course of the early and unsure levels of the pandemic.

“Given that COVID-19 appears to be overwhelmingly mild in children, our high estimate for symptomatic pediatric cases in Seattle suggests that there may have been thousands more mild cases at the time,” wrote Zhanwei Du, a postdoctoral researcher in Meyers’ lab and first writer on the examine.

According to a number of different research, about half of COVID-19 instances are asymptomatic, main researchers to consider that there could have been 1000’s extra contaminated individuals in Wuhan and Seattle earlier than every metropolis’s respective lockdown measures went into impact.

“We can go back and piece together the history of this pandemic using a combination of investigative techniques and modeling,” Meyers mentioned. “This helps us understand how the pandemic spread so quickly around the globe and provides insight into what we may see in the coming weeks and months.”

The new approach for estimating the quantity of unseen COVID-19 based mostly on the ratio of influenza instances to COVID-19 instances has additionally been used to find out what number of kids had been really contaminated in every metropolis and the tempo of the early pandemic within the U.S., Meyers mentioned.

The discovering within the new paper is per work that Meyers and her workforce have accomplished on the virus’s early spread. Using journey information, she and her workforce estimated how far the virus had spread and concluded that there have been as many as 12,000 instances of COVID-19 in Wuhan earlier than the lockdown.


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More data:
Zhanwei Du et al, Using the COVID-19 to influenza ratio to estimate early pandemic spread in Wuhan, China and Seattle, US, EClinicalMedicine (2020). DOI: 10.1016/j.eclinm.2020.100479

Citation:
Early spread of COVID-19 appears far greater than initially reported (2020, August 12)
retrieved 12 August 2020
from https://medicalxpress.com/information/2020-08-early-covid-greater.html

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