My kids are great about washing their hands at home, but I have no idea what kind of encouragement toward personal hygiene they get at school. The first thing I have them do when they get home is wash their hands. It does help!
I will say that now that my daughters are almost 8, they are not getting as sick as other kids their age. I think they got exposed to everything their first year of life.
It was a catch 22 for us and illnesses. We had to put my son in daycare when I went on bedrest during my pregnancy with my twins. We were originally going to pull him out after the girls were a few months old, but then they got the RSV and he stayed in daycare longer. Then one had severe asthma and the other had brain damage. I was constantly at the doctors or dealing with a sick kid, so my son stayed in daycare for another year. Unfortunately, he would bring home every illness. He rarely got sick, but my daughters would get sick.
I have mixed feelings about daycare. I don't know how we would have taken care of my son when I was on bedrest, but he brought home lots of illnesses.
I'm just glad my kids are older and don't get sick as often. We also get a flu shot every year. That helps a lot.