These infections can be either viral (most of the time) or bacterial. And there is almost no way to tell which one it is, at first. Since most of them are viral (contagious) the medical community is giving antibiotics less and less. And thank heaven for that! The catch; chances are the virus has already been passed around.
You can enforce/enact a 24hours on meds rule. Turn kids away that have fever PLUS runny nose, other cold symptoms, etc. My concern would be the kids comfort level. My handbook says that if the child is not able to participate in our daily activities, then they can't be here. Sounds harsh, but for me, I just think that a child that ill needs to be with mom/dad.