Personally I agree that you should close. If you were in a car accident and were hospitalized for a week you wouldn't be able to give them 30 days notice - this isn't much different.
But if you definitely can't close, what about offering the parents credit toward the following week's fees if they shorten their hours or keep their children home? Then have your employees care for the children while you camp out upstairs in case of emergency. IF you have to come downstairs do the mask, gloves, change clothes thing.
An ounce of prevention is worth a pound of cure...
