SEATTLE — Facing the nation’s first widespread coronavirus outbreak, some of Washington State’s top leaders quietly gathered on a Sunday morning last March for an urgent strategy session.

The virus had been rampaging through a nursing home in the Seattle suburbs. By the time the meeting began, the region had recorded most of the nation’s first 19 deaths. New cases were surfacing by the hour.

As the meeting’s presentation got to the fifth slide, the room grew somber. The numbers showed a variety of potential outcomes, but almost every scenario was a blue line pointing exponentially upward. ...