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

Table 2 Correlation of vitamin D concentrations with severe acute respiratory syndrome coronavirus 2 infections and outcomes

Ref.	n	Population type	Study type	Vitamin D dosages	Results
Lau et al[111], 2020	20	Adults, average age 65.2 yr	Retrospective observational study	NA	Higher levels of vitamin D deficiency were observed in ICU patients (84.6%) compared to baseline patients (57.1%) (P = 0.29)
Hastie et al[115], 2020	449	Adults, age 37–73 yr	Cross-sectional study	NA	Vitamin D levels showed a significant association with SARS-CoV-2 infection in univariate analysis (P = 0.013)
IIie et al[116], 2020	Cases and deaths/1 M population	Adults	Retrospective	NA	Negative correlation was observed between mean levels of vitamin D and COVID-19 cases (P = 0.050) and deaths (P = 0.053) per million population
Glicio et al[117], 2020	176	Adults, age ≥ 60 yr	Retrospective	NA	Severe patients are more likely than mild patients had a lower level of vitamin D
Tan et al[69], 2020	43	Adults, age ≥ 50 yr	Cohort observational	Vitamin D 1000 IU	Patients treated with vitamin D showed a significant protective effect against clinical deterioration after adjusting for age, sex and comorbidities (P = 0.041)
Darling et al[118], 2020	580 cases and 723 controls	Adults, average age 57.7 yr	Retrospective	NA	No significant difference was observed in vitamin D levels between COVID-19 cases and the control group
Raharusun et al[119], 2020	780 cases	Adults, average age 54.5 yr	Retrospective cohort study	NA	In univariate analysis, older and male cases with pre-existing medical conditions and below normal vitamin D levels were associated with higher mortality rates
Daneshkhah et al[120], 2020	5000 cases	Age ≤ 80 yr	As of March 21, 2020	NA	Approximately 15% reduction in the number of severe COVID-19 cases was observed in a population given a normal vitamin D status

NA: Not available; ICU: Intensive care unit; SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2; COVID-19: Coronavirus disease 2019.