Children under 7 years old have immature immune systems. Young children — especially those who may be attending school or daycare — are being exposed to new environments and new pathogens, or germs, that they haven’t experienced before.  At school or daycare, young kids may spread germs more easily because they don’t know how to cough or sneeze while covering their mouths. Younger children also tend to put their hands in their mouths, so the germs they touch on surfaces will end up being ingested. Learn more about why your child gets frequent colds and other viruses from a CHOC expert.