COVID-19 Variants of Concern (VOCs)

PHO is working with the Ontario Ministry of Health, the provincial testing network for COVID-19 and other laboratories, research and health care partners to test for and monitor COVID-19 variants of concern (VOCs) in Ontario.

Variants are viruses that have changed or mutated.

All viruses change over time and can lead to variants. While most variants have little impact on the properties of the virus and the impact it has on the community, some can have a larger impact.

Variants are common with coronaviruses, however, a variant becomes a VOC when its changes have a clinical or public health significance that affects one or more of the following:

  • transmissibility (spread)
  • virulence (severity of disease)
  • vaccine effectiveness
  • diagnostic testing

VOCs identified globally and in Ontario include:

World Health Organization label

PANGO lineage*









Omicron  B.1.1.529

*Includes all sub-lineages. For a full list of sub-lineages, please refer to our SARS-CoV-2 Whole Genome Sequencing in Ontario report. 

PHO is actively monitoring, reviewing and assessing international research on all evolving COVID-19 variants. Please see the Synopsis of Key Articles webpage for summaries of COVID-19 variant research.



Updated 27 April 2023