Table 1.

Classification of SARS-CoV-2 Variants.

	Pango Lineage and Corresponding WHO Naming	Attributes *
Variants of Interest	• B.1.525 (Eta) • B.1.526 (Iota) • B.1.617.1 (Kappa) • B.1.617.3 • C.37 (Lambda) ^ • B.1.621 (Mu) #	• Changes to receptor binding • Reduced neutralization by antibodies generated from previous infection or vaccination • Reduced efficacy of treatments • Potential diagnostic impact • Predicted increase in transmission and disease severity • Limited prevalence or expansion in the U.S. or other countries
Variants of concern	• B.1.1.7 (Alpha) • B.1.351 (Beta) • P.1 (Gamma) • B.1.617.2 (Delta)	• Attributes of variants of interest, but also includes: • Increase in transmissibility • More severe disease • Significant reduction in neutralization by antibodies generated during previous infection or vaccination • Reduced effectiveness of treatments or vaccines • Diagnostic detection failures and widespread interference with diagnostic test targets • Evidence of reduced vaccine-induced protection from severe disease
Variants of high consequences	• None (as of 17th September 2021)	• Attributes of variants of concern but also includes: • Demonstrated failure of diagnostics • Significant reduction in vaccine effectiveness, a high number of vaccine breakthrough cases, and very low vaccine-induced protection against severe disease • Significantly reduced susceptibility to multiple Emergency Use Authorization (EUA) or approved therapeutics • More severe clinical disease and increased hospitalizations

The classification is as per the Centers for Disease Control and Prevention (CDC) dated 17th September 2021. * As per the CDC definition. ^ The World Health Organization (WHO) named it the Lambda variant on 14th June 2021. ^# The World Health Organization (WHO) included the Mu variant as a variant of interest on 30th August 2021.