Overview of immunological & virological factors driving the evolution & global spread of SARS-CoV-2 variants.

The SARS-CoV-2, a highly infectious positive strand RNA virus first identified in December 2019, has produced multiple genetic variants that have rapidly and sequentially spread worldwide during the coronavirus disease 2019 (COVID-19) pandemic. Genetic changes in SARS-CoV-2 for greater infectivity, replication and transmission were selected during the early stages of the pandemic. More recently, after widespread infection and vaccination, SARS-CoV-2 variants that evade antigen- specific adaptive immunity, have begun to be selected. This article provides an overview of the molecular immunological and virological factors underlying the origin and global spread of important SARS-CoV-2 variant lineages.