The scientific literature on melatonin as a regulator in the immune system contains numerous evidence-based results on desired effects that can be useful in various viral infections. Researchers who have been working with melatonin for years and decades agree that these properties of melatonin could also be a sharp weapon in the battle with COVID-19. For this reason, the authors come to the conclusion that melatonin's considerable potential is being neglected. In treatment, possibly in the prevention of COVID-19 and also in dealing with the long-term effects of a virus infection, for example through brain-protective effects.