Runny nose, fever, cough, sore throat, even a headache can be the beginning of some type of sickness, especially in my kids= stay home, no jumping around, etc.
Vomitting/diarrhea or have been sick like that=stay home for at least 24 hours symptom free (actually I wouldn’t take my kids out until they were 100% better, and they were visibly better (eating solids, etc.) and could verbalize that. No way would we purposefully go anywhere if they even thought they had to have a bucket or had diarrhea, no way!
My husband is even more strict than I am. He doesn’t think you should ever knowingly be out sick and pass your germs around and hates to take our kids anywhere if they are even the slightest bit sick.
My inlaws have compromised systems and will insist the kids do not come over if they have even a runny nose, etc., so we respect that. At their age they cannot afford to get sick and these days seem to become more sick than they did years ago. My mom, same thing. She cannot afford to get sick as it can last 1-2 weeks and she is so miserable. We always let them know and give them the opportunity to decline visits or whatever. I know that they go out in public and are exposed to so many germs, etc., but knowing the kids (or we) are sick and knowingly passing our germs is would be kind of rude.