Table 3.

Summary of interventional studies of vitamin D supplementation associated with COVID-19 outcomes, studies involving single dose vitamin D supplementation have been excluded.

Study type	Study population	Aim	Results	Reference
Parallel pilot randomized open label, double-masked clinical trial	76 patients hospitalized with COVID-19	Effects of calcifediol treatment	Administration of a high dose of Calcifediol or 25-hydroxyvitamin D, significantly reduced the need for ICU treatment of patients requiring hospitalization due to proven COVID-19	Entrenas et al. (115)
Randomized placebo controlled	40 adults	Effect of high dose, oral cholecalciferol supplementation on SARS-CoV-2 viral clearance; daily 60 000 IU of cholecalciferol (oral nano-liquid droplets) for 7 days	Greater proportion of vitamin D-deficient individuals with SARS-CoV-2 infection turned SARS-CoV-2 RNA negative with a significant decrease in fibrinogen on high-dose cholecalciferol supplementation	Rastogi et al. (117)
Randomized, open label pilot study	50 adults hospitalized with COVID-19	Effect of treatment with calcitriol (0.5 μg/day for 14 days)	A significant reduction in oxygen requirements in patients who received calcitriol	Elamir et al. (31)
Randomized clinical trial	69 RT-PCR SARS-CoV-2 + hospitalized adults mild to moderate disease	Effect of 5,000 IU/day vs. 1,000 IU/day orally for 2 weeks of vitamin D3	5,000 IU daily oral vitamin D3 supplementation for 2 weeks reduces the time to recovery for cough and gustatory sensory loss among patients with sub-optimal vitamin D status and mild to moderate COVID-19 symptoms	Sabico et al. (118)