ABSTRACT: The COVID-19, caused by a novel coronavirus, was declared as a global pandemic by WHO more than five months ago, and we are still experiencing a state of global emergency. More than 74.30 million confirmed cases of the COVID-19 have been reported globally so far, with an average fatality rate of almost 3.0%. Seven different types of coronaviruses had been detected from humans; three of them have resulted in severe outbreaks, i.e., MERS-CoV, SARS-CoV, and SARS-CoV-2. Phylogenetic analysis of the genomes suggests that the possible occurrence of recombination between SARS-like-CoVs from pangolin and bat might have led to the origin of SARS-CoV-2 and the COVID-19 outbreak. Coronaviruses are positive-sense, single-stranded RNA viruses and harbour a genome (30 kb) consisting of two terminal untranslated regions and twelve putative functional open reading frames (ORFs), encoding for non-structural and structural proteins. There are sixteen putative non-structural proteins, including proteases, RNA-dependent RNA polymerase, helicase, other proteins involved in the transcription and replication of SARS-CoV-2, and four structural proteins, including spike protein (S), envelope (E), membrane (M), and nucleocapsid (N). SARS-CoV-2 infection, with a heavy viral load in the body, destroys the human lungs through cytokine storm, especially in elderly persons and people with immunosuppressed disorders. A number of drugs have been repurposed and employed, but still, no specific antiviral medicine has been approved by the FDA to treat this disease. This review provides a current status of the COVID-19, epidemiology, an overview of phylogeny, mode of action, diagnosis, and possible treatment methods and vaccines.
