Many of the typical illnesses found in daycare, including the common cold, stomach bugs, conjunctivitis and hand, foot mouth disease, are caused by viruses. There are spread through direct and indirect contact between children in close proximity who are likely to wipe noses, sneezing and coughing, while sharing toys and food.
My son get sick almost ever other week, cough and runny nose are already a common part of our lives. The only way to help is to make sure they are bathed once they are home. Ultimately, I think parents should keep their sick child at home instead of sending them to school and spread the viruses.