Viral Outbreaks of SARS-CoV1, SARS-CoV2, MERS-CoV, Influenza H1N1, and Ebola in 21st Century; A Comparative Review of the Pathogenesis and Clinical Characteristics

Throughout the past twenty years, humankind had its fair share of challenges with viral epidemics. In late December 2019, a zoonotic member of the coronaviruses was responsible for the COVID-19 outbreak of viral pneumonia in Wuhan, China. As a worldwide crisis, meanwhile, conclusive prevention or therapy has yet to be discovered, the death toll of COVID-19 has exceeded 278000 by May 11th, 2020. Alike other members of Coronavirus family such as MERS and SARS-CoV-1, SARS-CoV-2 provokes influenza-like syndrome which might further progress to the severe state of acute respiratory disease in some patients. Comparably, in 2009 the H1N1 influenza outbreak affected countless people by manifestations of respiratory system involvement. Additionally, Ebolavirus, as a member of the Filoviridae family, had also made a global catastrophe by causing hemorrhagic diseases in the past twenty years.  The unknown intrinsic nature of SARS-CoV-2, as a great missing piece of this pandemic puzzle, has had physicians to empirically test the possibly efficacious agents of the former viral epidemics on the COVID-19 cases. Here, the current knowledge in SARS-CoV-2 clinical features, transmissibility, and pathogenicity are all summed up as against the other emerging viruses in the last two decades, and the data crucially required for a better management of the illness has been spotlighted.