COVID-19 Morbidity in Healthcare Workers and Vitamin D Supplementation

\[Aim\] Purpose of the study: to analyze the effect of vitamin D supplementation in reducing COVID-19 morbidity and severity in healthcare workers. The study will involve a minimum of 120 medical staff. All participants in the study will assess twice for serum 25(OH)D level: baseline and after 3 months of Vitamin D supplementation. After the baseline examination, the subjects will be randomized into 2 groups. In the first (No. 1), vitamin D therapy will initiate at a dosage of 50,000 IU on the first and second week, followed by a switch to a daily intake of 5,000 IU for 3 months. In the second group (No. 2), vitamin D therapy will prescribe for 3 months at a dosage of 2,000 IU/day. After 3 months of vitamin D supplementation, all participants will undergo to repeat testing of serum 25(OH)D level with an assessment of the effectiveness of the therapy. Body mass index (BMI), height, weight, SARS-CoV-2 antibodies (IgG), 25-hydroxycalciferol (25(OH)D) and presence of acute viral infection futures, parameters assessed after treatment.