variants of sars-cov-2 variants of sars-cov-2 there are many variants of severe acute respiratory syndrome coronavirus 2 (sars-cov-2), the virus that causes coronavirus disease 2019 (covid-19). some are believed, or have been stated, to be of particular importance due to their potential for increased transmissibility, increased virulence, or reduced effectiveness of vaccines against them. these variants contribute to the continuation of the covid-19 pandemic. "new coronavirus variant" redirects here. for recent species of coronavirus, see novel coronavirus and coronavirus. part of a series on thecovid-19 pandemicscientifically accurate atomic model of the external structure of sars-cov-2. each "ball" is an atom. covid-19 (disease) sars-cov-2 (virus) cases deaths timeline 2019 2020 january responses february responses march responses april responses may responses june responses july responses august responses september responses october responses november responses december responses 2021 january responses february responses march responses april responses may responses june responses july responses august responses september responses october responses november responses december responses 2022 january responses february responses march responses april responses may responses june responses july responses august responses september responses october responses november december 2023 january february march april may locations by country and 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variants variants of concern alpha beta gamma delta omicron other variants epsilon zeta eta theta iota kappa lambda mu cluster 5 lineage b.1.617 economic impact and recession arts and culture aviation cannabis cinema films disney fashion financial markets food industry food security journalism music performing arts retail shipping television us sportscasting programs tourism video games by country canada india ireland malaysia new zealand russia uk us by sport association football baseball basketball combat sports cricket disc golf gaelic games gridiron football ice hockey motorsport rugby league impacts animals black people crime death rates by country disability domestic violence emergency evacuations education female environment hospitals language lgbt community long-term care media coverage mental health symptoms migration military notable deaths other health issues politics diplomacy popular culture protests pregnancy prisons religion catholic church hajj science and technology social media strikes suicides telehealth xenophobia and racism society ireland malaysia new zealand russia uk us covid-19 portal as of april 2023, only the omicron variant is designated as a circulating variant of concern by the world health organization. overview the origin of sars-cov-2 has not been identified. however, the emergence of sars-cov-2 may have resulted from recombination events between a bat sars-like coronavirus and a pangolin coronavirus through cross-species transmission. the earliest available sars-cov-2 viral genomes were collected from patients in december 2019, and chinese researchers compared these early genomes with bat and pangolin coronavirus strains to estimate the ancestral human coronavirus type; the identified ancestral genome type was labeled "s", and its dominant derived type was labeled "l" to reflect the mutant amino acid changes. independently, western researchers carried out similar analyses but labeled the ancestral type "a" and the derived type "b". the b-type mutated into further types including b.1, which is the ancestor of the major global variants of concern, labeled in 2021 by the who as alpha, beta, gamma, delta and omicron variants. early in the pandemic, the relatively low number of infections (compared with later stages of the pandemic) resulted in fewer opportunities for mutation of the viral genome and, therefore, fewer opportunities for the occurrence of differentiated variants. since the occurrence of variants was rarer, the observation of s-protein mutations in the receptor-binding domain (rbd) region interacting with ace2 was also not frequent. as time went on, the evolution of sars-cov-2's genome (by means of random mutations) led to mutant specimens of the virus (i.e., genetic variants), observed to be more transmissible, to be naturally selected. notably, both the alpha and the delta variants were observed to be more transmissible than previously identified viral strains. some sars-cov-2 variants are considered to be of concern as they maintain (or even increase) their replication fitness in the face of rising population immunity, either by infection recovery or via vaccination. some of the variants of concern show mutations in the rbd of the s-protein. the following table presents information and relative risk level for currently and formerly circulating variants of concern (voc). the intervals assume a 95% confidence or credibility level, unless otherwise stated. currently, all estimates are approximations due to the limited availability of data for studies. for alpha, beta, gamma and delta, there is no change in test accuracy, and neutralising antibody activity is retained by some monoclonal antibodies. pcr tests continue to detect the omicron variant. identification emergence changes relative to previously circulating variants at the time and place of emergence neutralising antibody activity (or efficacy when available) wholabel pangolineage nextstrainclade firstoutbreak earliestsample designated voc current circulation notable mutations transmissibility hospitalisation mortality from natural infection from vaccination delta b.1.617.2 21a india oct 2020 6 may 2021 no l452r, t478k, p681r +97% (76–117%) +85% (39–147%) relative to alpha +137% (50–230%) reinfections happened, with smaller occurrence rate than vaccinated infections efficacy reduction for non-severe disease omicron b.1.1.529 21k south africa 9 nov 2021 26 nov 2021 yes p681h, n440k, n501y, s477n, many others possibly increased −57% (59–61%) relative to delta −63% (69–74%) relative to delta increased reinfection rate efficacy reduction against symptomatic disease, unknown for severe disease alpha b.1.1.7 20i (v1) united kingdom 20 sep 2020 18 dec 2020 no 69–70del, n501y, p681h +29% (24–33%) +52% (47–57%) +59% (44–74%) minimal reduction minimal reduction gamma p.1 (b.1.1.28.1) 20j (v3) brazil nov 2020 15 jan 2021 no k417t, e484k, n501y +38% (29–48%) possibly increased +50% (50% cri, 20–90%) reduced retained by many beta b.1.351 20h (v2) south africa may 2020 14 jan 2021 no k417n, e484k, n501y +25% (20–30%) under investigation possibly increased reduced, t cell response elicited by d614g virus remains effective efficacy reduction against symptomatic disease, retained against severe disease very high risk high risk medium risk low risk unknown risk efficacy of natural infection against reinfection when available. 7 february – 22 june 22, 2021, ontario. cfr 0.04% for <50 age group unvaccinated, 6.5% for >50 age group unvaccinated differences may be due to different policies and interventions adopted in each area studied at different times, to the capacity of the local health system, or to different variants circulating at the time and place of the study. 1 april – 6 june 2021, scotland. another preliminary study in ontario found that hospitalization by delta increased by 120% relative to non-voc lineages. the study in israel tracked 46035 unvaccinated recovered and 46035 vaccinated people of the same age distribution, to compare their infection occurrence in the follow-up period. 640 infections in the vaccinated group and 108 infections in the recovered group were recorded. moderately reduced neutralisation with covaxin. b.1.1.7 with e484k assumed to only differ from b.1.1.7 on neutralising antibody activity. 23 november 2020 – 31 january 2021, england. cfr 0.06% for <50 age group, 4.8% for >50 age group the reported confidence or credible interval has a low probability, so the estimated value can only be understood as possible, not certain nor likely. march 2020 – february 2021, manaus. except pfizer–biontech. oxford-astrazeneca, novavax. nomenclature sars-cov-2 corresponding nomenclatures pango lineages notes to pango lineages nextstrain clades, 2021 gisaid clades notable variants a.1–a.6 19b s contains "reference sequence" wiv04/2019 b.3–b.7, b.9, b.10, b.13–b.16 19a l o b.2 v b.1 b.1.5–b.1.72 20a g lineage b.1 in the pango lineages nomenclature system; includes delta/b.1.617 b.1.9, b.1.13, b.1.22, b.1.26, b.1.37 gh b.1.3–b.1.66 20c includes epsilon/b.1.427/b.1.429/cal.20c and eta/b.1.525 20g predominant in us generally, feb '21 20h includes beta/b.1.351 aka 20h/501y.v2 or 501.v2 lineage b.1.1 20b gr includes b.1.1.207 and lambda (lineage c.37) 20d 20j includes gamma/p.1 and zeta/p.2 20f 20i includes alpha/b.1.1.7 aka voc-202012/01, voc-20dec-01 or 20i/501y.v1 b.1.177 20e (eu1) gv derived from 20a tree diagram of lineages of sars-cov-2 according to the pango nomenclature system. sars-cov-2 variants are grouped according to their lineage and component mutations. many organisations, including governments and news outlets, referred colloquially to concerning variants by the country in which they were first identified. after months of discussions, the world health organization announced greek-letter names for important strains on 31 may 2021, so they could be easily referred to in a simple, easy to say, and non-stigmatising fashion. this decision may have partially been taken because of criticism from governments on using country names to refer to variants of the virus; the who mentioned the potential for mentioning country names to cause stigma. after using all the letters from alpha to mu (see below), in november 2021 the who skipped the next two letters of the greek alphabet, nu and xi, and used omicron, prompting speculation that xi was skipped to avoid offending chinese leader xi jinping. the who gave as the explanation that nu is too easily confounded with "new" and xi is a common last name. in the event that the who uses the entirety of the greek alphabet, the agency considered naming future variants after constellations. various sars-cov-2 variants that were reported officially by cdc, nih, in may 2021 in relation to mutations l452r and e484k lineages and clades while there are many thousands of variants of sars-cov-2, subtypes of the virus can be put into larger groupings such as lineages or clades. three main, generally used nomenclatures have been proposed: as of january 2021, gisaid—referring to sars-cov-2 as hcov-19—had identified eight global clades (s, o, l, v, g, gh, gr, and gv). in 2017, hadfield et al. announced nextstrain, intended "for real-time tracking of pathogen evolution". nextstrain has later been used for tracking sars-cov-2, identifying 13 major clades (19a–b, 20a–20j and 21a) as of june 2021. in 2020, rambaut et al. of the phylogenetic assignment of named global outbreak lineages (pangolin) software team proposed in an article "a dynamic nomenclature for sars-cov-2 lineages that focuses on actively circulating virus lineages and those that spread to new locations"; as of august 2021, 1340 lineages had been designated. each national public health institute may also institute its own nomenclature system for the purposes of tracking specific variants. for example, public health england designated each tracked variant by year, month and number in the format /, prefixing 'vui' or 'voc' for a variant under investigation or a variant of concern respectively. this system has now been modified and now uses the format -, where the month is written out using a three-letter code. classification of variants variants that appear to meet one or more specific criteria considered during the covid-19 pandemic 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 in the us. 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. reference sequence as it is currently not known when the index case or "patient zero" occurred, the choice of reference sequence for a given study is relatively arbitrary, with different notable research studies' choices varying as follows: the earliest sequence, wuhan-1, was collected on 24 december 2019. one group (sudhir kumar et al.) refers extensively to an ncbi reference genome (genbankid:nc_045512; gisaid id: epi_isl_402125), this sample was collected on 26 december 2019, although they also used the wiv04 gisaid reference genome (id: epi_isl_402124), in their analyses. according to another source (zhukova et al.), the sequence wiv04/2019, belonging to the gisaid s clade / pango a lineage / nextstrain 19b clade, is thought to most closely reflect the sequence of the original virus infecting humans—known as "sequence zero". wiv04/2019 was sampled from a