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 ...

, which causes COVID-19, is a category used for variants of the virus where mutations in their

spike protein In virology, a spike protein or peplomer protein is a protein that forms a large structure known as a spike or peplomer projecting from the surface of an enveloped virus. as cited in The proteins are usually glycoproteins that form dimers ...

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 ''Smutsia' ...

nomenclature system and to clades in the

Nextstrain Nextstrain is a collaboration between researchers in Seattle, United States and Basel, Switzerland which provides a collection of open-source tools for visualising the genetics behind the spread of viral outbreaks. Its aim is to support public h ...

and

GISAID GISAID (Global Initiative on Sharing Avian Influenza Data) is a global science initiative and primary source established in 2008 that provides open access to genomic data of influenza viruses and the coronavirus responsible for the COVID-19 pan ...

systems. During the COVID-19 pandemic, 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 c ...

, 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 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 ...

: * 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 appe ...

" * 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 do ...

s (if and when such drugs are available) * Decreased susceptibility to neutralizing

antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

, either therapeutic (e.g., convalescent plasma or monoclonal antibodies) or in laboratory experiments * Ability to evade natural

immunity Immunity may refer to: Medicine * Immunity (medical), resistance of an organism to infection or disease * ''Immunity'' (journal), a scientific journal published by Cell Press Biology * Immune system Engineering * Radiofrequence immunity desc ...

(e.g., causing reinfections) * Ability to infect

vaccinated A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified. ...

individuals * Increased risk of particular conditions such as multisystem inflammatory syndrome 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 Who or WHO may refer to: * Who (pronoun), an interrogative or relative pronoun * Who?, one of the Five Ws in journalism * World Health Organization Arts and entertainment Fictional characters * Who, a creature in the Dr. Seuss book ''Horton Hea ...

maintains a list of variants of global concern. On 26 November 2021, the WHO added a fifth variant of concern, the

Omicron variant Omicron (B.1.1.529) is a variant of SARS-CoV-2 first reported to the World Health Organization (WHO) by the Network for Genomics Surveillance in South Africa on 24 November 2021. It was first detected in Botswana and has spread to become the ...

, previously known as B.1.1.529. Omicron joins the

Alpha Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , whic ...

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 labiod ...

Gamma Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter r ...

, and

Delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...

variants.

Africa

The NICD in

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

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

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 *