Oregon just closed its schools state wide starting Monday.
Closure is planned for two weeks.
Gov Kate Brown:

“However, I have heard from superintendents, school board members, teachers, parents, and students that it has now become impossible to functionally operate schools due to workforce issues and student absences. Schools are experiencing critical shortages in staff, and superintendents are concerned for school personnel who are at elevated risk such as those over age 60 and those with underlying medical issues.