This review gives an overview of the role of selenium deficiency on the development of several viral infectious diseases. According to numerous studies, selenium deficiency negatively affects the metabolic system, impairs the immune response, stimulates the progression of viral infectious diseases, and increases the number of harmful viral mutations. Additionally, some studies also showed that supplementation with selenium induces, among others, a decrease of viral mutations and an improved immune function. This review indicates that selenium levels should be monitored to control various viral infectious diseases. Further details can be found in the study.