Table 1.

Summary of the included articles in this review.

S. No.	Author and Year	Study design	Country (Study Setting)	Age (Mean ± SD)	Sample Size (I/C)	Participants	Intervention	Control/Placebo	Outcome	Remark	Outcomes studied
	Rastogi et al. 2020 [12]	Randomised, placebo controlled, study	India (Tertiary care hospital in north India)	–	16/24	Asymptomatic or mildly symptomatic SARS-CoV-2 RNA positive vitamin D deficient (25(OH) D < 20 ng/ml) individuals.	Daily 60,000 IU of cholecalciferol (5 ml oral solution in nano droplet form) for 7 days. Then weekly supplementation of 60,000 IU (if 25(OH)D > 50 ng/ml) else continued 60,000 IU for another 7 days up until day-14 in participants with 25(OH)D < 50 ng/ml	Placebo (5 ml distilled water for 7 Days)	Proportion of patients with SARS CoV-2 RNA negative before day-21 and change in inflammatory markers (D-dimer, fibrinogen, CRP, Prolactin)	Short term high-dose cholecalciferol supplementation	•D-dimer •CRP
	Murari et al. 2020 [16]	Multicentre, double-blind, parallel-group, randomized, placebo-controlled trial	Brazil (Clinical Hospital of the School of Medicine of the University of Sao Paulo (a quaternary referral teaching hospital) and from the Ibirapuera field hospital)	56.2 ± 14.4	119/118	Hospitalized patients with COVID-19 who were moderately to severely ill at the time of enrollment.	A single, oral dose of 200,000 IU of vitamin D3 dissolved in a 10-ml peanut oil solution	Placebo (10 ml of a peanut oil solution)	Length of stay, in-hospital mortality, admission to ICU, mechanical ventilation requirement	Single high dose of vitamin D3	•Mortality •ICU admission •Mechanical ventilation •D-dimer •CRP
	Castillo et al. 2020 [13]	Parallel Pilot randomized, open label, double-masked clinical study	Spain (Reina Sofia University Hospital, Cordoba, Spain EU)	53 ± 10	50/26	Hospitalized patients with COVID-19 clinical picture of acute respiratory infection, confirmed by a radiographic pattern of viral pneumonia and by a positive SARS-CoV-2 PCR with CURB65 severity scale.	Oral Calcifediol (0.532 mg soft capsules on day of admission; and 0.266 mg on day 3 and 7, and then weekly until discharge or ICU admission	Usual Care	ICU admission; Death	–	•Mortality •ICU admission •Mechanical ventilation
	Annweiler C. et al. 2020 [14]	Quasi-experimental study	France (Nursing home in Rhone, South East of France)	87.7 ± 9.3	57/9	Elderly nursing-home residents with COVID-19 and/or with physical disabilities, major neurocognitive and psychiatric disorders.	An oral bolus of 80,000 IU vitamin D3 either in the week following the suspicion or diagnosis of COVID-19, or during the previous month.	Usual Care	Mortality and Ordinal Scale for Clinical Improvement (OSCI) score in acute phase.	Single oral dose of 80,000 IU vitamin D3, either in the week following the suspicion or diagnosis of COVID-19, or during the previous month	•Mortality
	Annweiler G. et al. 2020 [15]	Quasi-Experimental Study	France (Angers University Hospital, France)	88 ± 5	16/32	Patients admitted for COVID-19 in a geriatric unit	Oral Vitamin D3 supplement of 80,000 IU within a few hours of the diagnosis of COVID-19	Usual Care	14-Day COVID-19 Mortality; Ordinal Scale for Clinical Improvement (OSCI) Score for COVID-19 in Acute Phase	80,000 IU vitamin D3 within a few hours of the diagnosis of COVID-19.	•Mortality