SARS-CoV-2 variants: National definitions, classifications and public health actions

Last updated: August 26, 2021

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Preamble

The Public Health Agency of Canada, in collaboration with provincial and territorial public health authorities, established the Canadian SARS-CoV-2 Variant Surveillance Group (CSVSG) to monitor and assess the impact of variants of SARS-CoV-2 on viral transmissibility, disease severity, and efficacy of vaccines, therapeutics, and diagnostics. The CSVSG has developed national definitions, classifications, and public health actions for SARS-CoV-2 Variants of Interest (VOI) and Variants of Concern (VOC).

Variant of interest

Definition

A SARS-CoV-2 variant is a VOI if it

has a genome with mutations associated with changes in epidemiology, antigenicity, or virulence, or changes that potentially have a negative impact on available diagnostics, vaccines, therapeutics, or public health measures;

and

is known to cause community transmission/multiple COVID-19 cases/clusters in Canada or has been detected in multiple countries;

or

is otherwise assessed to be a VOI by WHO;

or

is otherwise assessed to be a VOI by the CSVSG.

Actions

If a variant is determined to be a VOI, actions may include the following:

Table 1. Variants of interest. Updated August 05, 2021
WHO label Pango lineage Attributes Designation date
Epsilon B.1.427
B.1.429

Evidence of increased transmissibility Footnote 1

Evidence of moderate neutralization by some monoclonal antibody therapies Footnote 2

May 14, 2021
Zeta P.2

Predicted reduction in neutralization by some monoclonal antibody therapies

Predicted reduction in neutralization by polyclonal antibodies in convalescent sera

May 14, 2021
Eta B.1.525

Evidence of increased transmissibility Footnote 1

Predicted reduction in neutralization by some monoclonal antibody therapies

Predicted reduction in neutralization by polyclonal antibodies in convalescent sera

May 14, 2021
Theta P.3

Predicted reduction in neutralization by some monoclonal antibody therapies

Predicted reduction in neutralization by polyclonal antibodies in convalescent sera

May 14, 2021
Iota B.1.526
B.1.526.1

Evidence of increased transmission Footnote 1

Predicted reduction in neutralization by some monoclonal antibody therapies

Predicted reduction in neutralization by polyclonal antibodies in convalescent sera

May 14, 2021
Kappa B.1.617.1 Evidence of increased transmission Footnote 1
Preliminary evidence of impact on neutralization by convalescent and post-vaccination sera Footnote 3, Footnote 4
July 20, 2021
Lambda C.37 Preliminary evidence of moderate reduction in neutralization by convalescent and post-vaccine sera Footnote 5 July 20, 2021
n/a A.23.1

Predicted reduction in neutralization by some monoclonal antibody therapies

Predicted reduction in neutralization by polyclonal antibodies in convalescent sera

May 14, 2021
n/a B.1.1.318

Predicted reduction in neutralization by some monoclonal antibody therapies

Predicted reduction in neutralization by polyclonal antibodies in convalescent sera

May 14, 2021
n/a B.1.617.3

Predicted reduction in neutralization by polyclonal antibodies

Predicted reduction in neutralization by convalescent sera and post-vaccination sera

July 20, 2021
n/a B.1.621
B.1.621.1

Predicted reduction in neutralization by some monoclonal antibody therapies

Predicted reduction in neutralization by polyclonal antibodies

Predicted reduction in neutralization by convalescent sera and post-vaccination sera

August 05, 2021

Variant of concern

Definition

A SARS-CoV-2 variant is a VOC if, through a comparative assessment, it has been demonstrated to be associated with one or more of the following:

or

is otherwise assessed to be a VOC by WHO;

or

is otherwise assessed to be a VOC by the CSVSG.

Actions

If a variant is determined to be a VOC, actions may include the following:

Table 2. Variants of concern. Updated August 05, 2021
WHO label Pango lineage Attributes Designation date
Alpha B.1.1.7 Evidence of increased transmission Footnote 1
Evidence of increased severity Footnote 6, Footnote 7

Evidence of reduced neutralization by convalescent sera and post-vaccination sera Footnote 8Footnote 9Footnote 10
May 14, 2021
Beta B.1.351
B.1.351.1
B.1.351.2
B.1.351.3
B.1.351.4
Evidence of increased transmission Footnote 1
Evidence of increased severity Footnote 11
Evidence of impact on neutralization by polyclonal antibodies Footnote 2
Evidence of reduced neutralization by convalescent sera and post-vaccination sera Footnote 12,Footnote 8Footnote 13
May 14, 2021
Gamma P.1
P.1.1
P.1.2
Evidence of increased transmission Footnote 1
Evidence of increased severity Footnote 14, Footnote 15
Evidence of impact on neutralization by polyclonal antibodies Footnote 2
Evidence of reduced neutralization by convalescent sera and post-vaccination sera Footnote 16
May 14, 2021
Delta B.1.617.2
AY.1
AY.2
AY.3
AY.3.1
Evidence of increased transmission Footnote 1
Evidence of increased severity Footnote 17, Footnote 18
Evidence of impact on neutralization by polyclonal antibodies Footnote 3Footnote 4
Evidence of reduced neutralization by convalescent sera and post-vaccination sera Footnote 8Footnote 9
July 20, 2021

References

Footnote 1

Campbell, F et al. (2021) Increased transmissibility and global spread of SARS-CoV-2 variants of concern as at June 2021. Eurosurveillance doi: https://doi.org/10.2807/1560-7917.ES.2021.26.24.2100509

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Footnote 2

US FDA (2021) U. S. Fact sheet for health care providers emergency use authorization (Eua) of bamlanivimab and etesevimab. https://www.fda.gov/media/145802/download

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Footnote 3

Hoffmann, M. et al. (2021) SARS-CoV-2 variant B.1.617 is resistant to Bamlanivimab and evades antibodies induced by infection and vaccination. bioRxiv, doi: https://doi.org/10.1101/2021.05.04.442663

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Footnote 4

Liu, C. et al. (2021) Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell, doi: https://doi.org/10.1016/j.cell.2021.06.020

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Footnote 5

Tada, T. et al. (2021) SARS-CoV-2 Lambda Variant Remains Susceptible to Neutralization by mRNA Vaccine-elicited Antibodies and Convalescent Serum. bioRxiv, doi: https://doi.org/10.1101/2021.07.02.450959

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Footnote 6

Davies, N. G. et al. (2021) Increased mortality in community-tested cases of SARS-CoV-2 lineage B.1.1.7. Nature doi: https://doi.org/10.1038/s41586-021-03426-1

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Footnote 7

Challen, R. et al. (2021) Risk of mortality in patients infected with SARS-CoV-2 variant of concern 202012/1: matched cohort study. BMJdoi: http://doi.org/10.1136/bmj.n579

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Footnote 8

Nasreen, S. et al. (2021) Effectiveness of COVID-19 vaccines against variants of concern, Canada. medRxiv, doi: https://doi.org/10.1101/2021.06.28.21259420

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Footnote 9

Bernal, J. L. et al. (2021) Effectiveness of COVID-19 vaccines against the B.1.617.2 variant. medRxiv, doi: https://doi.org/2021.05.22.21257658

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Footnote 10

Cele, S. et al. (2021) Escape of SARS-CoV-2 501Y.V2 from neutralization by convalescent plasma. Nature, doi: https://doi.org/10.1038/s41586-021-03471-w

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Footnote 11

Jassat, W. et al. (2021) Increased mortality among individuals hospitalised with COVID-19 during the second wave in South Africa. bioRxiv, doi: https://doi.org/10.1101/2021.03.09.21253184

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Footnote 12

Madhi, S. A. et al. (2021)Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B.1.351 Variant. N. Engl. J. Med. doi: https://doi.org/10.1056/NEJMoa2102214

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Footnote 13

Lustig, Y. et al. (2021) Neutralizing Response against Variants after SARS-CoV-2 Infection and One Dose of BNT162b2. N. Engl. J. Med., doi: https://doi.org/10.1056/NEJMc2104036

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Footnote 14

Funk, T. et al. (2021) Characteristics of SARS-CoV-2 variants of concern B.1.1.7, B.1.351 or P.1: data from seven EU/EEA countries, weeks 38/2020 to 10/2021. Eurosurveillance, doi:https://doi.org/10.2807/1560-7917.ES.2021.26.16.2100348

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Footnote 15

Freitas, A. R. R. et al. (2021) The increase in the risk of severity and fatality rate of covid-19 in southern Brazil after the emergence of the Variant of Concern (VOC) SARS-CoV-2 P.1 was greater among young adults without pre-existing risk conditions. bioRxiv, doi: https://doi.org/10.1101/2021.04.13.21255281

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Footnote 16

Wang, P. et al. (2021) Increased Resistance of SARS-CoV-2 Variant P.1 to Antibody Neutralization. CSHL, doi: https://doi.org/10.1101/2021.03.01.433466

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Footnote 17

Sheikh, A. et al. (2021) SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness. Lancet, doi :https://doi.org/10.1016/S0140-6736(21)01358-1

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Footnote 18

Ong, S. W. X., et al. (2021). Clinical and Virological Features of SARS-CoV-2 Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.315 (Beta), and B.1.617.2 (Delta). SSRN, doi: https://doi.org/10.2139/ssrn.3861566

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