This book discusses the organ-specific systemic manifestations of COVID-19. The initial chapters of the book review the origin and evolution of the coronaviruses, followed by pathogenesis and immune response during COVID-19 infection. The book also provides insight into the role of angiotensin-converting enzyme 2 in the onset of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogenesis. It summarizes the neurological aspects of SARS-CoV2, including transmission pathways, mechanisms of invasion into the nervous system, and mechanisms of neurological disease. It also delineates the association of severe disease with high blood plasma levels of inflammatory cytokines and inflammatory markers in SARS-CoV-2 infection. Lastly, it discusses the perturbation of gut microbiota by SARS-CoV-2 and uncovers the potential risk of virus infection on reproductive health.