It's only the 2nd week of school for the kids and I'M the one who has the cold!!!
This is the way I explain it...during the Summer the kids are mostly outside where germs aren't so confined by 4 walls. Or the kids are at home where they're not exposed to so many germs. Once they start going to school, the germs have no where to go BUT to each other, desk surfaces, door knobs, pencils, bathrooms, etc. So of course once school starts there will be more illnesses going around.
All I can suggest is have your child eat healthy foods, drink lots of water, get plenty of sleep at night and constantly wash their hands. Every day my kids get home from school I have them wash their hands. It would be a good idea for them to change their school clothes as well. In the major sick months, like when the flu is going around or some sort of stomach virus, I have the kids drink an Airborne EVERY DAY after school. It's because of this routine that my son managed to be a part of that VERY SMALL percentage of kids who DID NOT get the stomach flu last year. At one point, way more than half of the school was out w/vomiting & diarreah. My son was NOT one of them.
Hope this helps!