Features of supply and approaches to the use of vitamin D in children in the post-COVID period

Vitamin D is an important component of immune function, and deficiency in childhood is associated with an increased risk of acute respiratory viral infections. Purpose. To assess the dynamics of vitamin D supply in children after a new coronavirus infection with the use of cholecalciferol. Material and methods. We examined 55 children aged 0–17 years (10.0 [9.2; 10.6] years), 52.7 % boys with COVID-19, who received cholecalciferol in a dose of 1000 to 3000 IU for 30 days in depending on the concentration of 25(OH)D. After 30 days of taking vitamin D3, the levels of total vitamin D in the blood serum were re-determined. Results. The median 25(OH)D level in children with COVID-19 was 24.5 [23.9; 26.7] ng/ml. 34.5 % of children had vitamin D deficiency status (≤ 20 ng/ml), 32.7 % had insufficiency (21–30 ng/ml), a third of patients had normal vitamin D status (≥ 30 ng/ml). As a result of treatment with cholecalciferol, the number of children with hypovitaminosis D decreased by 2 times (35.4 %, p < 0.05), with an adequate level — doubled (65.5 %, p < 0.05). Depending on the level of 25(OH)D, no statistically significant differences were found in the severity of coronavirus infection (χ² = 0.872, p = 0.929). Conclusion. In 2/3 of cases, children infected with SARS-CoV-2 had hypovitaminosis D. Children under 6 years of age were more likely to have vitamin D insufficiency, while patients 7–17 years of age had a deficiency. The distribution of vitamin D levels did not differ depending on the severity of coronavirus infection. Doses of cholecalciferol taken for 30 days were sufficient to increase the concentration of vitamin D in the blood serum of children with deficiency but did not reach standard values in patients with vitamin D deficiency.