The emergence of COVID-19 as a global pandemic: Understanding the epidemiology, immune response and potential therapeutic targets of SARS-CoV-2.

An acute respiratory disease caused by a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that surfaced in China in late 2019, continues to spread rapidly across the globe causing serious concerns. The coronavirus disease 2019 (COVID-19) is declared as a public health emergency worldwide by the World Health Organization (WHO). Increasing evidences have demonstrated human-to-human transmission that primarily affects the upper respiratory tract followed by lower respiratory tract damage leading to severe pneumonia. Based on the current status, the elderly population and people with prior co-morbidities are highly susceptible to serious health effects including cytokine up-regulation and acute respiratory distress syndrome (ARDS). Currently, COVID-19 research is still in the preliminary stage necessitating rigorous studies. There is no specific drug or vaccine targeting SARS-CoV-2 currently and only symptomatic treatment is being administered, but several antivirals are under active investigation. In this review, we have summarized the epidemiology, entry mechanism, immune response, and therapeutic implications, possible drug targets, their ongoing clinical trials, and put forward vital questions to offer new directions to the COVID-19 research.