Infectious diseases, especially viral infections, have emerged as a major concern for public health in recent years. Recently emerged COVID-19, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has been declared a pandemic by World Health Organization since March 2020. It was first identified in Wuhan, China, in December 2019 and has since claimed more than a million lives. Complicated symptoms are associated with rising incidence and fatality rates, while many of the vaccine candidates are in the final stages of clinical trials. This review encompasses a summary of existing literature on COVID-19, including the basics of the disease such as the causative agent's genome characterization, modes of transmission of the virus, pathogenesis, and clinical presentations like associated immune responses, neurological manifestations, the variety of host genetic factors influencing the disease and the vulnerability of different groups being affected by COVID-19.