New modeling suggests that if the spread of the novel coronavirus is not slowed, there could be 25,000 infections in King and Snohomish counties by April 7, with 400 of those people likely to die.

This modeling is apparently one of the factors Gov. Jay Inslee and other local leaders consulted before instituting one of the harshest emergency responses in state history, restricting gatherings of more than 250 people across King, Pierce and Snohomish counties on Wednesday in an effort to prevent spread of the virus. The order is leading to the cancellation of concerts, sporting events, large church services, conventions and festivals.

Researchers at The Institute for Disease Modeling in Bellevue, the Bill & Melinda Gates Foundation and the Fred Hutchinson Cancer Research Center released a working paper on March 11 using research from around the world on coronavirus, and local research from the flu — including a study of how much school cancellations around 2019’s “Snowpocalypse” reduced spread of the flu.

During an interview on CNN on Wednesday evening, Seattle Mayor Jenny Durkan quoted the research and said it spurred leaders to act.

“If you look at those numbers and the trajectory, this virus is in community spread now, and not just in Seattle,” Durkan said.

The researchers wrote that a 25 percent reduction in transmission rate, which is likely achievable with social-distancing measures the state and county already implemented, would lower the total number of infections to 9,700 and result in about 160 deaths.

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“The model shows that any social distancing that results in reduced transmission rates will slow the rate of growth of the epidemic,” the study authors wrote, “but only large changes in contact rate can interrupt ongoing transmission.”

It will take more aggressive measures to lower transmission by 75 percent – which is what the modeling suggests will be necessary to stem the outbreak. That would result in less than 2,000 cases and around 30 deaths by April 7, the study suggests.

In total, 29 people in Washington state are known to have died from the disease as of Wednesday , and there were a total 366 cases in Washington state. Schools around the region have closed for weeks, employees at many of the region’s tech companies are working from home, and many concerts and sports events have been canceled or are being played in empty stadiums.

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