Trial of Vitamin D Supplementation in infants with Bronchiolitis, A Randomized, Double-Blind, Placebo-Controlled Study Khaled Saad 1* , Nafisa H.R. Abd Aziz 1 , Amira A. El- Houfey 2 , Osama El-Asheer 1 , Sherif A.A. Mohamed 3 , Ahmed E. Ahmed 4 , Khaled A. Abdel Baseer 4 , Manal M. Darwish 5 . Affiliations: 1 - Department of Pediatrics, Faculty of Medicine, Assiut University, Assiut, Egypt. 2 - Department of Community Health Nursing, Faculty of Nursing, Assiut University, Egypt. 3 - Department of Chest Diseases, Faculty of Medicine, Assiut University, Assiut, Egypt. 4 - Department of Pediatrics, Qena Faculty of Medicine, South Valley University, Egypt. 5 - Department of Public Health & Community Medicine, Faculty of Medicine, Assiut University, Assiut, Egypt. *Address correspondence to Khaled Saad, Department of Pediatrics, Faculty of Medicine, Assiut University, Assiut City 71516, Egypt. Tel: +20-100-608-0182. Fax: +20-88-236-8371. E-mail: ksaad8@ yahoo.com, khaled.ali@med.au.edu.eg Short running title: Trial of Vitamin D in Bronchiolitis. Keywords: Bronchiolitis; Vitamin D; Infants; Clinical trial. Abbreviations: ARI: Acute respiratory infections; RSV: Respiratory syncytial virus. Funding Source: No funding was secured for this study. Financial Disclosure: The authors have no financial relationships relevant to this article to disclose. Conflict of Interest: All authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.