Genetic sleuths told the story of how coronovirus started in Washington

A detailed genetic analysis of the strains of the virus that cause COVID-19 suggests that the outbreak occurred in late January or early February in Washington state, but did not last for weeks.

This is the culmination of two studies published by the journal Science, based on varying attempts to find the genetic fingerprint of a coronavirus known as SARS-CoV-2.

The study draws on an analysis of more than 10,000 samples collected in the Paget Sound region, thousands of more samples from other regions of the world, as part of the Seattle Flu Study during the early weeks of the outbreak.

One of the studies was conducted by a team including Trevor Bedford, a biologist at Seattle’s Fred Hutchinson Cancer Research Center who has been continuing to assess the virus and its spread since the early days of the outbreak. The first edition of the team’s paper went online back in March and was revised in May, in the months before today’s peer-reviewed publication.

Other studies have been conducted by researchers led by Michael Verboy of the University of Arizona, who also published an initial version of their results in May.

There are subtle differences between the two analyzes. For example, Bedford and his colleagues state that it is most likely that the majority of infections in Washington State originated from a single case that was introduced in late January or early February.

However, Warboy’s team suggested that many travelers returning from China during that time frame may have brought the virus to Washington and California.

This schematic map shows the introduction of the initial and apparently “dead-end” SARS-CoV-2 to Europe and America (dashed arrow). Successful dispersal between late January and mid-February is shown with solid arrows: from Hubei Province, China, northern Italy; From China to Washington State; And later, from Europe (more widely known as the Italian outbreak) to New York City and China to California. (Credit: Andrew Rambut / University of Edinburgh and Jeffrey Joy / University of British Columbia)

Bedford and his colleagues say that there is not yet enough evidence to rule out the hypothesis that the community of coronoviruses began with a previously reported case, known as WA1, that occurs on 19 January. But the second team’s analysis, which includes other aggregates, spread the virus, argues against that scenario.

Varobe and his colleagues also argued against the possibility that the virus had arrived in Washington state via British Columbia, an alternative scenario suggested by the data. Instead, they say it is more likely that the virus jumped directly from China.

At the time, foreign travelers were barred from coming to the US from China, but tens of American citizens and visa holders continued to travel even after the ban was imposed. Verbobe and his co-authors state that a similar scenario separated the virus from Europe into the US East Coast through China.

Both studies suggest that close monitoring of COVID-19 cases based on a model established by the Seattle Flu Study may mitigate the effects of the epidemic in the US, but in a news release, Verboi said a silver for researchers Layer. Sad conclusion

“Our research shows that when you intervene early and find out well, it can have a wider impact, both preventing and controlling epidemics once they occur,” Warboe said. “While the epidemic was finally tripped up, there were early victories that showed us the way forward: extensive trials and case identification are powerful weapons.”

Trevor Bedford, Alex Greninger, Pavitra Roychowdhury, Lee Starita and Michael Famulare are the lead authors of “Cryptic Transmission of SARS-CoV-2” in Washington State. Jay Shendre and Keith Jerome are senior authors – and scores of co-authors, including investigators with the Seattle Flu Study.

In addition to Verbobe, the authors of “The Emergence of SARS-CoV-2 in Europe and North America” ​​include Jonathan Pecker, Brendan Larsen, Martha Nelson, Verity Hill, Jeffrey Joy, Andrew Rambout, Mark Suchard, Joel Worthheim and Philip Lemmy.

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