COVID-19: a review on SARS-CoV-2 origin, epidemiology, virology, clinical manifestations and complications with special emphasis on adverse outcome in Bhopal Gas Tragedy survivor.

After the global outbreak of coronaviruses caused diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS), an outbreak due to these viruses occurred in December, 2019 in Wuhan, Hubei Province, China and led to a worldwide spread. Coronavirus 2019 disease (COVID-19) has emerged as a serious global health emergency and spread from a person to another who has the virus. But the scope of an intermediate host is not known. Population at higher risk includes individuals in higher age group (>60 years) or with comorbidities such as diabetes, hypertension, cardiovascular disease and weaker immune system. Many unknown and underestimate risk factors could be responsible for adverse outcomes in COVID-19. These risk factors should be appropriately identified, addressed and necessary actions should be taken to mitigate the effect of COVID-19 pandemic. Bhopal gas tragedy was one of the world's worst industrial chemical leak disaster. The survivors of this incident still suffer from the various complications such as increased rate of cancers, chronic illness like tuberculosis, respiratory diseases, birth defects, nerve injury, growth retardations, gynecological illness and many more. The survivors of Bhopal gas tragedy are at higher risk of developing COVID-19 related adverse outcome. One of the possible explanations can be long term effect of methyl isocyanate (MIC). MIC exposure can lead to possible toxic effect on genetic, epigenetic and non-genetic factors. In this review, we aim to establish the scientific basis for adverse outcome in COVID-19 patients who are also victims of Bhopal gas tragedy.