Think about when a disaster hits; everyone waits for that 'declaration' so that it will trigger a federal response which then makes the area eligible for federal assistance.
While we've all been working, raising families, dealing with life for decades, those in elected positions have made sure things are incorporated into the various state governments which passes down to the counties and then the cities/towns.
In 1918/1919 the world saw a pandemic the likes of which it hadn't seen since the bubonic plague.No shutdown.And IIRC that one killed people of all ages and in all states of health.This one kills the elderly,those in nursing homes and those with pre-existing conditions.Special advice can be given to those people and the rest of the nation can go about its business.