Table 5.

Studies on the investigation of the vitamin D role in combating COVID-19.

Study Type	Study Design	Parameter Examined	Findings	Ref
Clinical Trials	Multi center, open-label, randomized controlled trial, Vitamin D 50,000 IU daily orally to 260 COVID19 Patients of age ≥ 65 years.	All Causes of mortality.	Vitamin D supplementation at high doses might be an efficient, well-tolerated, and quickly available therapy for COVID-19.	[112]
	Household cluster-randomized with a planned pragmatic, double-blinded trial, 2700 subjects 1:1 ratio vitamin D 3200 IU/d v/s Placebo.	The likelihood of hospitalization and/or fatality among newly diagnosed people.	Lowering hospitalization and/or death rates in recently diagnosed patients, as well as avoiding infection within their intimate infected persons	[113]
	Open-label randomized parallel pilot, double-blinded trial, 76 COVID-19 hospitalized patients.	ICU admissions and fatalities rate	The use of calcifediol has been shown to minimize the requirement for ICU care in individuals who require hospitalization. COVID-19	[109]
	Randomized Multicenter clinical trials, 69 COVID-19-positive patients, 5000 IU/d (n = 36); 1000 IU/d (n = 33) for two weeks orally.	Gustatory sensory loss and cough recovery	The time it takes for patients to recover from gustatory sensory loss and cough is reduced by taking 5000 IU of vitamin D3 daily for two weeks.	[114]
	65 hospitalized COVID-19 positive patients of age between 63–89 years.	Commodities, Type of respiratory involvement, laboratory parameters (vitamin, C-reactive protein, D, D-dimer), Pulmonary parameters (PaO2/FiO2, PaCO2, PaO2, and SO2)	Vitamin D insufficiency is linked to more serious respiratory involvement, a lengthier illness period, and a higher chance of mortality.	[112]