It feels like your child is always sick. One kid in the class sniffles on Monday, and by Thursday your child is down with it. Daycare sends home another note about something going around, and it moves straight through your house. And when your child does catch a cold, it seems to linger for weeks after the other kids have bounced back.
First, an important distinction. A cold is a viral illness, a real virus your child's body has to recognize, fight, and clear. That is different from allergies, where the immune system overreacts to harmless things like pollen. Here is the question worth asking: why do some children move through cold season barely touched while others catch all of it? The difference is rarely the exposure. Every kid in that classroom is breathing the same air. The difference is how well the immune system is being regulated, and the immune system is regulated by the nervous system.