Vitamin D Thwarts winter colds and flu in children

A study about to come out in Pediatrics (and noted by NIH's Medline web site) shows that giving daily Vitamin D supplements to children with LOW levels of Vitamin D reduces their susceptibility to winter colds and flu.  Conducted by Mass General Hospital researchers, but in Mongolia where there is an ample supply of  non-sunlight in winter.  Also, lots of kids deficient in Vitamin D in the winter.  Perhaps Mongolian milk isn't fortified with Vitamin D. (This last sentence reveals my utter lack of knowledge of modern life in Mongolia.) So, American kids might do better in winter on Vitamin D levels even without supplements.
But, what if your kid doesn't like milk and doesn't drink enough --4 glasses a day at the very least --to keep levels up?  Has your  pediatrician  tested his/her Vitamin D  levels? If not, you might gently suggest at the next visit (especially one in the winter time) that you'd like the doctor to test Vitamin D, or at least ask him or her whether it has been tested in the past (in the winter time).