In conclusion, in the index study, significantly low serum
25(OH)D levels were found in children with RRI and chronic
cough. Co-administration of supplementary 5000 IU/day vitamin
D for 3 mo together with conventional treatments may
be appropriate in the prophylaxis of RRI and chronic cough.
The simple intervention of vitamin D supplementation appears
promising in helping to prevent infections and chronic
cough in children