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

Last updated: August 18, 2022

On this page

• Overview
• Variant of concern (VOC)
• Variant of interest
• De-escalation
• Risk assessments

Overview

The Public Health Agency of Canada established the Federal SARS-CoV-2 Variant Surveillance Group (FSVSG) 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 FSVSG has developed national definitions, designations, and public health actions for SARS-CoV-2 Variants of Interest (VOI), Variants of Concern (VOC), and De-escalated Variants. Descendent lineages inherit the classification of the parent lineage unless otherwise designated. Note that the VOI designation relates to surveillance status and is not a statement of the level of concern associated with a given variant.

Variant of concern (VOC)

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:

• increased transmissibility or detrimental change in COVID-19 epidemiology;
• increased virulence or change in clinical disease presentation;
• decreased effectiveness of available diagnostics, vaccines, therapeutics, or public health measures;

or

is otherwise assessed to be a VOC by the World Health Organization (WHO);

or

is otherwise assessed to be a VOC by the FSVSG.

Actions

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

• Notification to WHO under the International Health Regulations.
• Perform enhanced genomic and case-based surveillance.
• Submit complete genome sequences and accompanying contextual data to public sequence repositories (e.g., GISAID, INSDC).
• Perform epidemiological investigations that include appropriate disaggregation by age, sex, gender, race/ethnicity, Indigeneity, socioeconomic status, and geography/place of residence as data is available to improve understanding of the potential impacts of the VOC on COVID-19 spread, severity, the effectiveness of vaccines and public health measures, or other relevant characteristics.
• Perform laboratory investigations to assess the impact of the VOC on diagnostic methods, immune responses, antibody neutralization, or other relevant characteristics.

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 FSVSG.

Actions

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

• Perform enhanced genomic and case-based surveillance.
• Submit complete genome sequences and accompanying contextual data to public sequence repositories (e.g., GISAID, INSDC).
• Perform epidemiological investigations that include appropriate disaggregation by age, sex, gender, race/ethnicity, Indigeneity, socioeconomic status, and geography/place of residence as data is available to improve understanding of the potential impacts of the VOI on COVID-19 spread, severity, the effectiveness of vaccines and public health measures, or other relevant characteristics.
• Perform laboratory investigations to assess the impact of the VOI on diagnostic methods, immune responses, antibody neutralization, or other relevant characteristics.

No currently circulating lineages are designated VOIs in Canada.

De-escalation

The SARS-CoV-2 virus continuously evolves, generating new lineages. Over time, some lineages may become prevalent while others will become extinct and no longer pose a threat to public health.

A VOC is de-escalated when:

• the VOC prevalence is ≤ 1% in the national genomic surveillance system each week (non-averaged/cumulative) for ≥ 4 consecutive weeks and one of more of the following;
• there is a large decrease in severity indicators (hospitalizations, ICU admissions, deaths) when compared to current predominant VOC variant; or
• there is evidence that the VOC does not demonstrate a decrease in effectiveness of available diagnostics, vaccines, therapeutics, or public health measures compared to the predominantly circulating strain; or
• the VOC is otherwise de-escalated as a VOC by WHO or other international health organizations.

A VOI is de-escalated as warranted after review by the FSVSG.

Risk assessments

• Risk assessments for COVID-19 variants of concern