There is an urgent need for new supportive treatment options against infectious viral diseases, given the rapid spread and huge number of individuals affected worldwide by these diseases, so cost-effective, globally available and safe options with minimal side effects and simple application are highly assured. This study will therefore discuss the potential of vitamin D supplementation as a preventive and therapeutic agent in combination with other strategies, as this vitamin meets all the criteria described above. A variety of data are available on the association of vitamin D with respiratory infections and viral infections, as well as on the immune response by supplementation with this vitamin.Vitamin D deficiency adds to the variables that make people more susceptible to infection and the damaging development of COVID-19, as there is a correlation between its levels in the body and the severity of COVID-19 infections. Due to its direct antiviral and anti-inflammatory properties, it can be assumed that maintaining it within normal levels in the body is necessary to maintain the health of the body, and when its level in the body is below the optimal level, this can be compensated for with vitamin D supplements.