A Comprehensive Review on the Emergence of COVID-19, Variants, Diagnosis, Treatment, and Vaccination

Abstract

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) marked one of the most significant global health crises of the twenty-first century. This virus, responsible for coronavirus disease 2019 (COVID-19), has rapidly evolved into multiple variants with differing transmissibility, pathogenicity, and potential for immune escape. The global response has involved rapid advancements in diagnostic tools, antiviral treatments, immunomodulatory therapies, and the unprecedented development of vaccines. This review summarizes the origin of SARS-CoV-2, the biological behavior of its variants, diagnostic strategies, treatment approaches, and the development and deployment of vaccines. It highlights the lessons learned from the evolving pandemic and emphasizes the importance of ongoing surveillance, preparedness, and global cooperation.