Dr. Jeff Duchin, the public health officer for Seattle and King County, said that while the impacts have already been significant, he believed that the region was still in the early phase of an epidemic that was likely to last months.

“We expect a large-scale outbreak in weeks, and this will be a very difficult time,” Dr. Duchin said.

In Seattle, the disruptions have already been rippling through the region, one of the fastest growing economies in the country, and almost no one has been untouched by either the virus or the broadening attempts to keep it at bay.

Traffic has largely vanished, and on ferries crossing Elliott Bay, passengers who normally get out of their cars and socialize on deck have started staying in their cars. On neighborhood Facebook groups, posts looking for plumber recommendations have been replaced with pleas for protective wear for medical professionals, offers to swap child care and GoFundMe campaigns. An “artists relief fund” has raised more than $37,000; another for homeless services has raised at least $22,000.

Sylvain Berthe, the general manager of Local 360, grew emotional as he sat Wednesday inside his empty restaurant, now permanently closed after the business saw a sudden and precipitous decline in both regular diners and private events over the past few weeks.