This book provides up-to-date insights into the COVID-19 disease, addressing its outbreak, pathogenesis, biology, treatment interventions, and consequences as a global health crisis. Divided into six sections, the book covers a detailed examination of various facets of the disease. Section I delves into the host's genetic and epigenetic mechanisms in response to COVID-19. Section II focuses on disease diagnosis, providing valuable perspectives on kits, nucleic acid testing, immunological assays, imaging-based diagnosis, and variant-specific SARS-COV-2 detection. Section III covers cytokine storm, inflammation, and immunity, including the modulation of signaling pathways leading to immune evasion and persistence. Section IV reveals drug repurposing, exploring antiviral, anti-inflammatory, anti-platelet drugs, and target-based drug discovery. Section V explains the evolution of vaccine development including DNA, RNA, subunit, and viral vaccines. Finally, Section VI explores COVID-19's impact on associated comorbidities, ranging from cancer and cardiac issues to neurological damages and economic consequences. The book is relevant for scientists, and researchers working on pathogenesis, development, implementation, host-pathogen interactions, and drug repurposing of COVID-19 disease.