Is it true that kids attending daycare are sick more often than those who are not?

Yes: Typically yes (but not always!) most children exposed to other young children in daycare are more likely to get colds and other common childhood illnesses. This is simply because there are more individuals around to share germs. In the long run, exposure to common childhood illnesses early on is beneficial to the immune system, and most "daycare" babies end up being healthy children later on.

Yes: Yes, of course. Part of growing up is getting sick. The immune system actually depends on it. It works on memory, so getting sick helps prime it for the future. Thus, kids are sick very often and lots of kids around lots of sick kids equals all those kids passing illness around on a consistent basis. However, this is all part of growing up and those who dont get sick now will at school age.