What is the Impact of Vitamin D Levels on COVID-19 Severity?: A Systematic Review
Objective: We assessed studies probing at vitamin D deficiencies in both positive and negative COVID-19 cases.
Methods: We measured mean, standard deviations, and 95% Confidence Interval (CI) of many studies to determine if there is a consistent relationship between vitamin D levels and COVID-19. Independent sample t-test compared non-survivors vs. survivors of COVID-19 and vitamin D levels, and moderate vs. severe COVID-19 symptoms and vitamin D levels.
Results: We evaluated the difference in vitamin D levels (serum 25(OH)D, nmol/L) among those who tested positive for COVID-19 to those who tested negative. The average median serum 25(OH)D, nmol/L for patients who tested positive was 27.08 nmol/L (± 0.58 SD, 95% CI: 1.88) and the average median of serum 25(OH)D, nmol/L for patients who tested negative was 48.67 nmol/L (± 13.66 SD, 95% CI: 2.17) this difference was near significant (p=0.059). When looking at the relationship between vitamin D levels and severity of COVID-19 progression the result was not statistically significant, t(df)=0.84, p=0.216. When comparing the average values of vitamin D level among those who survived COVID-19 vs. those who did not the results were not statistically significant, t(269)=0.17, p=0.438.
Conclusion: There seems to be a correlation between vitamin D deficiency and likelihood of developing severe illness of COVID-19 when observing studies individually. However, when comparing studies on a larger scale it seems that the significant difference seems to fade.