I use to run a playgroup so I researched this alot in order to make an effective "sick policy" for our playgroup. Here are the guidelines that I posted.
Kids get colds, it's a fact of life. Runny noses happen and young children are prone to put things in their mouths. Its impossible to keep all illness away but but in order to try to keep our play group as healthy as possible we ask that you please do not attend an event is your child has any of the following symptoms of illness:
•Cold symptoms starting within the last 48 hours - A cold is contagious within the first 2 days of symptoms.
•diarrhea within the last 48 hours
•vomiting within the last 48 hours
•a fever within the last 48 hours
•eye drainage, blood shot eyes, yellow or green nasal secretions.
•sore throat
•cough and fever within the last 48 hours
•spot-like rash following low-grade fever and tiredness (might be chicken pox)
•been on antibiotics for less than 48 hours
For all other illnesses that are contagious for an extended period of time or illnesses that put young children or pregnant women at risk of hospitalization or cause other detrimental consequences, please ask your family doctor when it is safe for you to return to play dates. In some cases a Doctor's note may be requested before you attend play dates again.