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Infectious Diseases

Variants of Concern and Mutations of Interest (VOC/MOI)

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  • The Alpha (B.1.1.7) and Delta (B.1.617.2) variants of concern (VOCs), are the most identified VOCs in Simcoe Muskoka. As of July 30, 2021 there are a total of 5,058 variant cases (alpha (B.1.1.7), beta (B.1.351), gamma (P.1), delta (B.1.617.2)) and Mutations of Interest (MOI)/screened positive cases). As of June 17, 2021, the Simcoe Muskoka District Health Unit, along with 10 other Ontario public health units, was declared a hot spot for the Delta (B.1.617.2) VOC.
    • As of July 27, all cases reported on or after May 23, 2021 which are negative for both the E484K and N501Y mutations are considered presumptive Delta (B.1.617.2) cases and will be included in variant case counts. Previously these were treated as screened negative. This change may result in a shift in several variant-related metrics, including total variant cases and percent positivity.
  • As of July 30, 2021, there are zero active COVID-19 outbreaks that have known variant cases.
  • The 7-day moving average of new VOC/screened positive cases increased significantly from 15 cases per day in early March 2021 to over 80 cases per day by late April; however, this decreased to around 2 cases per day by mid-July (Note: not including the most recent days due to reporting delays).
  • Starting in June, the proportion of COVID-19 cases identified as the Delta (B.1.617.2) VOC began increasing, while the proportion of cases identified as the Alpha (B.1.1.7) VOC began decreasing. Delta (B.1.617.2) has been the dominant VOC in Simcoe Muskoka since mid-June, and has been identified in over 50% of VOC cases since the beginning of July.
  • The Delta (B.1.617.2) variant has been classified as a VOC by the Public Health Agency of Canada.  
    • All B.1.617 cases are currently presumed to be of the Delta (B.1.617.2) lineage as it is the dominant B.1.617 strain in Ontario.
  • Estimates suggest that the Alpha (B.1.1.7) VOC is 36% to 75% more contagious than the original COVID-19 strain. The Gamma (P.1) and Beta (B.1.351) VOCs are also associated with increased transmissibility. (Public Health Ontario. Interim Guidance for Infection Prevention and Control of SARS-CoV-2 Variants of Concern for Health Care Settings. February 2021).
  • Compared with early variants of COVID, VOCs are associated with a 63% increased risk of hospitalization, a 103% increased risk of intensive care unit (ICU) admission and a 56% increased risk of death due to COVID-19. (Ontario COVID-19 Science Advisory Table. COVID-19: Variants of Concern. April 20, 2021).
  • For outbreaks in which 1 or more cases have been laboratory confirmed to have a VOC, there is a higher degree of certainty that other cases in the outbreaks will also have the VOC.
  • Screening practices for VOCs and mutations of interest may vary at the discretion of Public Health Ontario, based on public health priorities and public health lab capacity.
    • As of June 14, 2021, the provincial COVID-19 whole genome sequencing strategy sends all eligible positive COVID-19 samples (from the COVID-19 diagnostic test) for whole genome sequencing as part of their surveillance strategy. This strategy will help detect new and emerging variants in a more proactive and timely way.
    • From May 26 to June 13, the provincial genome sequencing strategy was a sampling-based method, with 50% of all eligible positive COVID-19 test results being sequenced using whole genome sequencing (WGS), along with targeted samples of specific SARS-CoV-2 cases (e.g. travel, outbreak and coroner requests).
    • From February 3 to May 25, 2021, Public Health Ontario (PHO) and the Provincial Diagnostic Laboratory Network screened all new positive COVID-19 specimens for known VOCs, to rapidly identify and mitigate against spread of VOCs in Ontario.
  • Emerging VOCs have mutations in the virus genome that alter the characteristics and cause the virus to act differently in ways that are significant to public health. It’s important to understand that genetic mutations are expected, and some variants can spread and become predominant while others subside. Information on VOCs, including Alpha (B.1.1.7) and others, can be accessed here.
  • The WHO has released new guidelines for naming Covid-19 VOCs and variants of interest, using the Greek alphabet in place of country of origin.
  • Public health measures needed to help address the variant are the same as those in place right now. Visit SMDHU’s website for ‘Stop the Spread’ information as well as Public Health Ontario’s Evidence Brief on Public Health Measures Required for Rapid Control of Variants of Concern.
  • Visit Public Health Ontario’s website for additional information about the different types of VOCs

Variant Outbreaks with Variants of Concern Cases and/or Positive Screen Cases, Simcoe Muskoka

Variant Outbreaks with Variants of Concern Cases and/or Positive Screen Cases Declared by Week, Simcoe County and Muskoka District

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Variant of Concern Cases and/or Positive Screen Cases by Type of Case, Simcoe County and Muskoka District

7 Day Rolling Average of New COVID-19 Cases with a Variant of Concern (VOC) or a Screened Positive Result, Simcoe Muskoka

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Weekly COVID-19 Variants of Concern (VOCs) by Percent or Counts, Simcoe Muskoka

Technical Notes and Definitions

Please see Technical Notes and Definitions here.

Page Last Modified: July 30, 2021