I actually get really cross when people with the flu go out and about. If someone with a compromised immunity catches the flu, it could be life threatening.
If my DD has a mild cold, she will be sent to school. But anything else, she's home. I know there's a couple of kids at school with seriously compromised immunity and so I don't risk it for them. I got really annoyed when a child was sent to holiday program when they were very sick and of course DD got it and then I got it. Some common courtesy would be nice.