Can Vitamin D Help Prevent Respiratory Infections?

As a parent, you want to do everything you can to protect your kids and prevent them from getting sick. You read the news. You follow health blogs. You get email notifications about prevention tips. One of the ideas you may have encountered is this: Vitamin D helps prevent respiratory infections. Does this idea contain some grain of truth?
What Causes Indoor Air Pollution? Learn How To Breathe Healthy (Infographic)

Are you aware of the stuff that you use at home that make you sick?