This comes from a producer of probiotics so its veracity is questionable, but nevertheless--there may be something to this. An excerpt from MedPage Today:
When given preventively over the winter months, probiotics reduce fever, cough, and runny noses in children, researchers said.
Prophylactic Lactobacillus acidophilus alone or in combination with other microorganisms reduced the incidence and duration of all three symptoms, Gregory J. Leyer, PhD, of Danisco USA in Madison, Wis., and colleagues reported online in Pediatrics. Danisco produces probiotics and other health foods.
"Daily probiotic dietary supplementation during the winter months was a safe, effective way to reduce episodes of fever, rhinorrhea, and cough, the cumulative duration of those symptoms, the incidence of antibiotic prescriptions, and the number of missed school days attributable to illness," the researchers said...