Does the melatonin supplementation decrease the severity of the outcomes in COVID-19 patients? A mini review of observational data in the in vivo and in vitro studies

The Coronavirus Disease 2019 (COVID-19) is a global pandemic and there is no specific treatment for reducing the severity of this disease up to date. The majority of the treatments remain supportive and empirical. The aim of present study is to assess the relationship between melatonin supplementation and its effect on the severity of the outcomes in covid-19 patients. All published studies up to April 4 of 2021 were searched by using the databases of PubMed, ISI Web of Science, SCOPUS and Google Scholar.  Finally, 201 studies have been acquired.      After screening titles, abstracts and justifying the inclusion criteria, eight studies were finally selected in our study. Four studies were observational and case series with total 216,792 participants. Three studies performed on laboratory in the molecular level and one was carried out in mice. The results have suggested that melatonin decreases the severity of the outcomes of COVID-19 patients in their early stage or even in their critical conditions. Furthermore, the melatonin decreases pneumonia and reduces the ground glass lung damage observed in the image findings. Also, it plays an important role as anti-inflammatory, anti-viral and antioxidant activities. Melatonin inhibits the main protease of sares-cov-2 virus and decreases the viral load in molecular level. Regarding the in vivo studies, melatonin is more effective for reducing acute lung injury than other treatments. Although, further clinical studies are required.