Abstract
Vitamin D insufficiency is associated with poor prognosis in COVID-19 patients. Vitamin D supplementation is related to improved clinical outcomes in terms of intensive care unit admission and death, particularly in individuals with moderate-to-severe forms of COVID-19. The placebo-controlled five-day study was performed on 99 hospitalised COVID-19 patients with vitamin D insufficiency randomised into two groups. Vitamin D in the form of a sublingual sprayable microemulsion was given three times daily (daily dose 12,000 IU) to 51 patients with blood 25(OH)D levels below 30 ng/ml. Forty-eight patients in the control group received a placebo spray in the same daily regimen. Intention-to-treat (ITT) analysis and pre-protocol analysis were used to verify the impact of 25(OH)D level elevation on inflammatory markers. There was a statistically significant increase by 8.7 ± 7.6 ng/ml in 25(OH)D level from the baseline level of 15.6 ± 6.5 ng/ml in the case group. Individuals with moderately severe disease showed negative correlation between changes in 25(OH)D and C-reactive protein (CRP) levels in both ITT and pre-protocol analysis (p < 0.05). Mild and severe cases showed no statistical significance in CRP levels. There were no statistically significant changes in ferritin and IL-6 levels in ITT and pre-protocol analysis. In conclusion, high-dose vitamin D therapy was accompanied by significant decrease in CRP levels in COVID-19 patients with a moderate to severe illness.