Crappy immune systems

I used to brag about how my kids never get sick, but since this school year has started it seems like my kids keep getting sick. My son had a virus a few weeks ago that had to just run it's course, then my daughter got it. Now, my daughter has an ear infection and just today my son started complaining about his head and throat hurting and is now running a fever. What am I doing wrong?! Well, not what am I doing wrong but what can I do to hopefully boost their immune systems. Seriously, what has changed?

Just more viruses out there this year maybe? Just make sure everyone washes their hands regularly and wipe down surfaces with disinfectant. There's not much else you can do unfortunately. The good thing is that they're building better immune systems by getting sick. I know it sucks in the meantime though  

Quoting ~*Lette*~:" Just more viruses out there this year maybe? Just make sure everyone washes their hands regularly and ... [snip!] ... The good thing is that they're building better immune systems by getting sick. I know it sucks in the meantime though  "

It majorly sucks, especially because I have a test tomorrow.