Study aim: Assessment of the effect of vitamin D supplementation among patients with the diagnosis of 2019 Novel Coronavirus infection Design: Clinical trial containing group control, with parallel groups, double blind, randomized, third phase on 210 patients. Block method will be used for randomization. Settings and conduct: Interventions in three groups will be performed as below: Group 1: 50000 International Unit (IU) vitamin D supplementation and then 10000 IU supplementation daily Group 2: 1000 IU vitamin D supplementation daily Blood samples will be taken before and after the intervention. This study will be done in Mashhad-Iran. Blinding will be performed for patients and investigators. Participants/Inclusion and exclusion criteria: Age 30- 60 years old; serum vitamin D level lower than 30 nano gram per milliliter; cases who diagnosed as COVID-19 infection by clinical features; laboratory findings (positive C Reactive Protein, lymphocyte lesser 1100 per milliliter); serum vitamin D level upper than 30 nanogram per milliliter; use of vitamin supplements; use of immune suppressants or medications that interfere with vitamin D metabolism; history of nephrolithiasis; kidney disorders requiring dialysis or current malignancy diagnosis; pregnancy or lactating. Intervention groups: The 50000 International Unit (IU) vitamin D supplement weekly and then 10000 IU vitamin D supplement daily and the 1000 IU vitamin D supplement daily Main outcome variables: Chest X-ray findings, CT scan findings, Length of stay, Serum vitamin D level, Serum C-Reactive Protein level, Serum Erythrocyte Sedimentation Rate level, Serum neutrophil to lymphocyte ratio, Fasting Blood Glucose, Low Density Lipoprotein, High Density Lipoprotein, Triglyserid, Total cholesterol