Role of vitamin D in COVID-19 and other viral infections

Table 4 Summary of current studies examining the use of vitamin D in coronavirus disease 2019 and other viral infections conditions

Ref.	n	Vitamin D type	Vitamin D dosage	Application method	Viral infection	Disease status	Results
Entrenas Castillo et al[61], 2020	76	Vitamin D3 (calcifediol)	0.532 mg on day 1, then 0.266 mg on days 3 and 7, and weekly thereafter	Oral	SARS-CoV-2	Mild–moderate	The need for intensive care and the mortality rate were lower in patients receiving vitamin D treatment
Murai et al[62], 2021	240	Vitamin D3 (cholecalciferol)	200000 IU loading dose	Oral	SARS-CoV-2	Mild–moderate	High-dose vitamin D treatment did not improve clinical outcomes of COVID-19 patients
Rastogi et al[63], 2020	40	Vitamin D3 (cholecalciferol)	60000 IU/d for 7 d	Oral	SARS-CoV-2	Light	Vitamin D treatment shortened the time to PCR negativity
Maghbooli et al[64], 2020	235	Vitamin D3 (cholecalciferol)	50000 IU/wk	Oral	SARS-CoV-2	Mild–moderate	Adequate vitamin D levels shortened hospitalizations and reduced rates of serious illness
Annweiler et al[65], 2020	77	Vitamin D3 (cholecalciferol)	80000 IU single dose	Oral	SARS-CoV-2	Moderate–severe	COVID-19-related mortality rates were lower in patients receiving vitamin D therapy
Cangiano et al[66], 2020	90	Vitamin D3 (cholecalciferol)	25000 IU/mo	Oral	SARS-CoV-2	Moderate–severe	Severity of COVID-19 symptoms decreased in older individuals with vitamin D deficiency
Giannini et al[67], 2021	100	Vitamin D3 (cholecalciferol)	100000 IU/mo	Oral	SARS-CoV-2	Mild–moderate	High doses of vitamin D were found to be effective in reducing complications due to COVID-19
Ling et al[68], 2020	50	Vitamin D3 (cholecalciferol)	400 IU/d	Oral	Respiratory tract infections	Mild–moderate	Vitamin D supplementation has been found effective in reducing the incidence of respiratory infections
Tan et al[69], 2020	43	Vitamin D3 (cholecalciferol)	1000 IU/d	Oral	SARS-CoV-2	Moderate–severe	Vitamin D supplementation was found to be effective in reducing hospital stay and complications

SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2; COVID-19: Coronavirus disease 2019.