The high mortality
of deadly virus infectious diseases including SARS, MERS, COVID-19, and avian
flu is often caused by the uncontrolled innate immune response and destructive
inflammation. The majority of viral diseases are self-limiting under the help
of the activated adaptive immune system. This activity is cell proliferation
dependent and thus, it requires several weeks to develop. Patients are
vulnerable and mortality usually occurs during this window period. To control the
innate immune response and reduce the inflammation during this period will
increase the tolerance of patients and lowers the mortality in the deadly virus
infection. Melatonin is a molecule that displays respective properties, since
it downregulates the overreaction of the innate immune response and
overshooting inflammation, but also promotes the adaptive immune activity. Many
studies have reported the beneficial effects of melatonin on deadly virus
infections in different animal models and its therapeutic efficacy in septic
shock patients. Furthermore, melatonin has a great safety margin without
serious adverse effects. We suggest the use of melatonin as an adjunctive or
even regular therapy for deadly viral diseases, especially if no efficient
direct anti-viral treatment is available.