We have a rule, too sick for school = too sick for anything else. If DS tells us he is not up to going to school then there is no Scouts, baseball/basketball, Ninja Warrior, after school club. A quick reminder of that will normally get him motivated for school. We know when he is really sick because he is ok with missing event X.

I don't get parents sending sick kids to anything. They need to be home resting.

And yes, I am aware that my kid spread his germs before he was not able to go to school.

You do realize that the healthy kid who is having a party is going to spreading those flu germs to everyone, right?