My younger son has always been a bit of a germ magnet, and if I closed every time he got sick I would have gone out of business

When ever either of my kids are sick I always let the parents know right away, text or email in the middle of the night and/or phone call in the morning. I let them know what the symptoms are and leave the decision up to them of whether they want to send their kids here or not. If they decide to keep their kids home, they are not charged for the day. If they decide to send their kids, they risk having their kids pick up whatever illness my children have and know they will need to keep their kids home until they are better.