Since the WHO declared coronavirus disease 2019 (COVID-19) as a pandemic, huge efforts were made to understand the disease, its pathogenesis, and treatment. COVID-19 is caused by severe acute respiratory syndrome (SARS) coronavirus-2 (SARS-CoV2), which is closely related to SARS-associated coronavirus (SARS-CoV). This article attempts to provide a timely and comprehensive review of the coronaviruses over the years, and the epidemics they caused in this century with a focus on the current pandemic COVID-19. It also covers the basics about the disease immunopathogenesis, diagnosis, prognosis, and treatment options. Although almost every single week new clinical findings are published, which change our understanding of COVID-19, this review explores and explains the disease and the treatment options available so far. In summary, many therapeutic options are being investigated to treat and/or ameliorate the symptoms of COVID-19, but none is registered and no sufficient data to support immune-based therapy beyond the context of clinical trials. For that, strengthening our immune system is the best defense at this time.