Genetic variants of SARS-CoV-2 have been emerging and circulating around the world throughout the COVID-19 pandemic. Viral mutations and variants in the United States are routinely monitored through sequence-based surveillance, laboratory studies, and epidemiological investigations. In collaboration with the SARS-CoV-2 Interagency Group (SIG), CDC established a classification scheme for variants of SARS-CoV-2:
A variant with specific genetic markers that have been associated with changes to receptor binding, reduced neutralization by antibodies generated against previous infection or vaccination, reduced efficacy of treatments, potential diagnostic impact, or predicted increase in transmissibility or disease severity. Possible attributes of a variant of interest:
A variant for which there is evidence of an increase in transmissibility, more severe disease (increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures. Possible attributes of a variant of concern (in addition to the possible attributes of a variant of interest):
The B.1.1.7, B.1.351, P.1, B.1.427, and B.1.429 variants circulating in the United States are classified as variants of concern.
A variant of high consequence has clear evidence that prevention measures or medical countermeasures (MCMs) have significantly reduced effectiveness relative to previously circulating variants. Possible attributes of a variant of high consequence (In addition to the possible attributes of a variant of concern):
Currently there are no SARS-CoV-2 variants that rise to the level of high consequence.
Table Current variants in the United States.