Abstract
More than 5 years have passed since the emergence of the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), yet this virus continues to circulate globally, undergoing evolutionary changes. The effective control of SARS-CoV-2 necessitates an understanding of its antigenicity, replicative capacity, pathogenicity and transmissibility, as well as the development of preventive and treatment options. In this Review, we describe the origins and evolution of SARS-CoV-2, and outline variant and subvariant-specific characteristics. We also discuss the challenges faced in implementing prevention and treatment methods, such as the emergence of antigenically distinct variants and the phenomenon of immune imprinting. This Review provides insights into combating the ongoing COVID-19 pandemic and guidance for future research and vaccine development efforts.