SARS-CoV-2 variant of concern

The term variant of concern (VOC) for SARS-CoV-2, which causes COVID-19, is a category used for variants of the virus where mutations in their spike protein receptor binding domain (RBD) substantially increase binding affinity (e.g., N501Y) in RBD-hACE2 complex (genetic data), while also being linked to rapid spread in human populations (epidemiological data).^[1]

Before being allocated to this category, an emerging variant may have been labeled a variant of interest (VOI),^[2] or in some countries a variant under investigation (VUI).^[3] During or after fuller assessment as a variant of concern the variant is typically assigned to a lineage in the Pango nomenclature system^[4] and to clades in the Nextstrain^[5] and GISAID^[6] systems.

During the COVID-19 pandemic, the SARS-CoV-2 virus has been observed to mutate, with certain combinations of specific point mutations proving to be more concerning than others.^[7] This was principally for reasons of transmissibility and virulence, and also with regard to the possible emergence of escape mutations.