Despite a significant dose-dependent increase in serum 25-hydroxyvitamin D (25(OH)D) concentrations in children receiving vitamin D3 supplements (5600 IU/week and 11,200 IU/week), the trial reported no significant reduction in the number of ARIs, ARI hospitalizations, changes in LL-37/cathelicidin concentrations, or adverse events, indicating that higher internal vitamin D concentrations did not correlate with fewer respiratory infections. This evidence concerns the gene CAMP and respiratory tract infectious disorder.