ABSTRACT
Vitamin D is fat soluble vitamin synthesis from isoprenoid units by condensation process in vivo when exposure to sun light (weak UV source). The main function of vitamin D is maintenance on calcium hemostasis, beside this function has important role as a protection factor from many disease such as autoimmune diseases and cancer. There are several suggestions to support the immunity such as intake vitamin D that has the ability to reduce the risk of respiratory tract infections, such as epidemiology of influenza and COVID-19. Vitamin D can reduce the risk of COVID-19 infection through the mechanisms including lowering replication of virus by induction of cathelicidins and reduced the inflammatory cytokines that produced from the lining cells of lungs which lead to pneumonia and lung fibrosis due to autoimmune diseases as well as increase the concentrations of anti-inflammatory cytokines.