The term variant of concern (VOC) for

SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus that causes COVID-19 (coronavirus disease 2019), the respiratory illness responsible for the ongoing COVID-19 pandemic. The virus previously had a No ...

, which causes

COVID-19 Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019. The disease quickl ...

, 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). Before this, an emerging variant may have been labeled a variant of interest, or in some countries a variant under investigation. During or after fuller assessment as a variant of concern the variant is typically assigned to a lineage in the

PANGOLIN Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: ''Manis'', '' Phataginus'', and '' Smuts ...

nomenclature system and to clades in the Nextstrain and GISAID systems. During the

COVID-19 pandemic The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identified ...

, the SARS-CoV-2 virus has been observed to mutate, with certain combinations of specific

point mutation A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. Point mutations have a variety of effects on the downstream protein product—consequences ...

s proving to be more concerning than others. This was principally for reasons of transmissibility and

virulence Virulence is a pathogen's or microorganism's ability to cause damage to a host. In most, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its ability to ...

, and also with regard to the possible emergence of escape mutations.

Criteria

Several national and international health organisations (e.g.

Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georg ...

(CDC) (US),

Public Health England Public Health England (PHE) was an executive agency of the Department of Health and Social Care in England which began operating on 1 April 2013 to protect and improve health and wellbeing and reduce health inequalities. Its formation came as a ...

(PHE) and the

COVID-19 Genomics UK Consortium The COVID-19 Genomics UK Consortium (COG-UK) is a group of public health agencies and academic institutions in the United Kingdom created in April 2020 to collect, sequence and analyse genomes of SARS-CoV-2 as part of COVID-19 pandemic in the Un ...

for the UK, and the Canadian COVID Genomics Network (CanCOGeN)) use some or all of the following criteria to assess

variants Variant may refer to: In arts and entertainment * ''Variant'' (magazine), a former British cultural magazine * Variant cover, an issue of comic books with varying cover art * ''Variant'' (novel), a novel by Robison Wells * "The Variant", 2021 e ...

: * Increased transmissibility * Increased morbidity * Increased mortality * Increased risk of "

long COVID Long COVID or long-haul COVID (also known as post-COVID-19 syndrome, post-COVID-19 condition, post-acute sequelae of COVID-19 (PASC), or chronic COVID syndrome (CCS)) is a condition characterized by long-term health problems persisting or app ...

" * Ability to evade detection by diagnostic tests * Decreased susceptibility to

antiviral drug Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs d ...

s (if and when such drugs are available) * Decreased susceptibility to neutralizing antibodies, either therapeutic (e.g., convalescent plasma or monoclonal antibodies) or in laboratory experiments * Ability to evade natural immunity (e.g., causing reinfections) * Ability to infect vaccinated individuals * Increased risk of particular conditions such as

multisystem inflammatory syndrome Multisystem inflammatory syndrome may refer to: * Multisystem inflammatory syndrome in children (also known as 'paediatric multisystem inflammatory syndrome'), a rare life-threatening illness resembling Kawasaki disease that has been observed follo ...

or long-haul COVID. * Increased affinity for particular demographic or clinical groups, such as children or

immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...

individuals. Variants that appear to meet one or more of these criteria may be labeled "variants of interest" or "variants under investigation" ('VUI') pending verification and validation of these properties. Once validated, variants of interest /VUI may be renamed "variants of concern" by monitoring organizations, such as the CDC. A related category is "variant of high consequence", used by the CDC if there is clear evidence that the effectiveness of prevention or intervention measures for a particular variant is substantially reduced.

Classifications by country

World Health Organization

The WHO maintains a list of variants of global concern. On 26 November 2021, the WHO added a fifth variant of concern, the Omicron variant, previously known as B.1.1.529. Omicron joins the Alpha,

Beta Beta (, ; uppercase , lowercase , or cursive ; grc, βῆτα, bē̂ta or ell, βήτα, víta) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Modern Greek, it represents the voiced labi ...

, Gamma, and Delta variants.

Africa

The NICD in

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring count ...

maintains a list of variants and testing facilities locally in collaboration with

KRISP The University of KwaZulu-Natal (UKZN) is a university with five campuses in the province of KwaZulu-Natal in South Africa. It was formed on 1 January 2004 after the merger between the University of Natal and the University of Durban-Westville. ...

Europe

As of November 2021, the European Centre for Disease Prevention and Control declared four variants to be 'variants of concern': Beta, Gamma, Delta, and B.1.1.529 (named 'Omicron' after the reference was updated); Mu, Lambda and AY.4.2 were named as Variants of Interest (VOI), while there were 9 'Variants under monitoring'. 25 variants were described as 'de-escalated'.

United Kingdom

As of November 2021, the United Kingdom has fifteen variants on its 'watch list', 4 with 'VOC' status and 11 rated as 'VUI'. Those designated 'VOC' were Alpha, Beta, Gamma, and Delta. In early December 2021, Omicron was added to the VOCs. Among the Variants under investigation is 'VUI-21OCT-01/ A.Y 4.2'.

North America

Canada (via health-infobase.canada.ca) and the United States (via the CDC) also maintain lists of variants of concern. As of early December, Canada was monitoring five variants of concern: Alpha, Beta, Gamma, Delta, and Omicron, while the US was monitoring two: Delta and Omicron.SARS-CoV-2 Variant Classifications and Definitions
Dec. 1, 2021 ''www.cdc.gov'', accessed December 7, 2021

References

{{Coronaviridae *