ABSTRACT
The overview of scientific information concerning actual characteristics of population's supply with vitamin D and its role in case of risk of development of infectious diseases and COVID-19 is presented. The analysis established that vitamin D deficiency contributes both to higher risk of susceptibility to infectious agent and to negative impact to course and outcome of disease. The significant role of vitamin D in prevention and treatment of viral diseases is established. The international research studies confirm that at infectious diseases and early stages of COVID-19 protective immune response is responsible for elimination of the virus. Therefore, using vitamin D in treatment of COVID-19 is the strategy of immune protection. The authors consider that in case of infectious risks, preventive application of vitamin D is necessary. In case of initial manifestations of COVID-19, it is appropriate to promptly achieve levels of optimal status of micro-nutrient supply.