The number of upper respiratory infections will decrease as children grow older and their immunities have increased. As hard as it is to see your young child not feeling well, illness is an important part of building immunities. Regrettably, the answer is no, it wouldn't help to send them home. A child has been highly communicable for three days before the cold symptoms appear. The virus has already spread to those who were susceptible.
Colds are more prevalent in winter than in summer.
One of the reasons for the high occurrence during winter months is that we are indoors more and in close contact with others. Contrary to folk sayings, colds are not spread by cold air or drafts. They are spread by hand contact, coughing and sneezing. One of the most important measures we have to prevent spread of germs is hand washing. Requiring hand washing upon arrival at and before departure from school is based on our knowledge of germs and germ pools.