COVID-19- Variants of Concern (VOC)

Last Reviewed/Updated: 8:56 a.m., June 11, 2021


Viruses are known to mutate over time. This can cause variants, or different strains, of the same virus. New variants can be different from the original virus in their transmissibility and the severity of disease they cause.  They can also escape the impact of a vaccine, if they are not recognizable to the immune system.  And they can lead to re-infection in people who have already had a different strain of the same virus.

With COVID-19, the variants of concern (VOC) tend to be more highly transmissible.  This means that the virus spreads more easily between people.  Community members will need to layer all public health measures to prevent transmission.  This includes:

  • Maintaining 2-metres of distance from non-household members
  • Wearing a mask when distancing is not possible – even outdoors
  • Practicing hand hygiene
  • Covering coughs and sneezes
  • Disinfecting high touch surfaces

To learn more about how to reduce your risk, click here. For information on the local COVID-19 variant cases, visit the Local COVID-19 Tracker.

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What are the COVID-19 variants
How are the cases of the variant identified?
What should you do to prevent the transmission of VOCs
FAQ: Covid-19 variants of concern

What are the COVID-19 variants

Four variants of concern have been identified:

Alpha (B.1.1.7)

  • Detected in Ontario in December 2020.
  • Spreads more easily (53-82% more transmissible).
  • Increased severity of disease with a higher risk of hospitalization and death.
  • Both Pfizer and Moderna indicated that their COIVD-19 vaccines appear to be effective against the Alpha variant. This is likely because the part of the virus that changed doesn’t impact how the vaccine works.

Beta (B.1.351)

  • Detected in Ontario in February 2021.
  • Spreads more easily (50% more transmissible).
  • May escape impact of a vaccine and evade the immune response.

Gamma (P.1)

  • May escape impact of a vaccine and evade the immune response.

Delta (B.1.617.2)

  • There are different sublineages associated with this variant: B.1.67.1, B.1.67.2, B.1.67.3
  • Two lineages (B.1.67.1 and B.1.67.2) spreads more easily.
  • About 50% more transmissible than the Alpha variant.

Experts continue to study how the virus is changing by understanding its genetic make-up.  This will help us understand how changes to the virus might affect how it spreads, or how it presents in people.

Find the number of cases for each of the variants in Ontario here.

How are the cases of the variant identified?

Peterborough Public Health and the Public Health Ontario Labs are watching closely for any VOCs.  Once a positive COVID-19 test is received it is screened for VOCs.  This process can take 1-2 days.  Due to the delay, PPH is treating all positive cases of COVID-19 as a VOC for contact tracing and management purposes.  By doing so, PPH will be able to respond more quickly id the COVID-19 test screens positive for a variant.

If the test does screen positive for a VOC, then the Public Health Ontario Lab carries out genomic sequencing to determine the precise variant.  Genomic sequencing can take up to 14 days.

The first case of a variant in Peterborough was identified on February 23, 2021.  For more information on the local COVID-19 variant cases, visit the Local COVID-19 Tracker.

What you should do to prevent the transmission of VOCs

Everyone is encouraged to continue following the COVID-19 – Guidance for Everyone  to prevent the transmission of COVID-19 and its variants.  All the recommendations should be followed to reduce the risk of transmission.  The safest option is to restrict all non-essential travel and to socialize only with household members.  Residents are also asked to stay local, and to not travel between health unit regions or have guests from other regions visit.

Individuals who qualify for the limited exemptions for wearing a mask are encouraged to wear a face shield instead of a mask or to stay at home.  We recommend that these individuals make use of online ordering and delivery options.  Following these recommendations is the safest option, especially to prevent the spread of COVID-19 variants.

If you suspect that you have been in contact with a case of COVID-19, or you are experiencing COVID-19 symptoms, seek testing and isolate until you receive your test results.  Once you do receive the results, follow the public health recommendations associated with your diagnosis.

FAQ: COVID-19 variants of concern

Where did the variants come from?
What is a virus variant?
Are the variants more transmissible or contagious?
How are cases with variants identified?
How do we stop the spread of variants?
How many variant cases are in Ontario right now?
What is the difference between presumed and confirmed VOC cases on the Local COVID Tracker?
What is PPH doing to protect against the variants?
How do we protect ourselves against the variants?

What is a virus variant?

Viruses are known to mutate and change over time to create new variants or strains.  Mutations are common among other coronaviruses as well.  To be considered a variant of concern, the new strain of the virus must have clinical or public health significance that affects one or more of the following: transmissibility (how quickly it spreads), severity of disease, vaccine effectiveness, and diagnostic testing

Are the variants more transmissible or contagious?

Alpha variant: Early modelling indicates that this strain may be between 56-70% more transmissible.  Contact tracing investigations in the UK show that the secondary attack rate may be higher than other variants (15.1% versus 9.8%).  This means that the number of close contacts of a confirmed COVID-19 case who become positive for COVID-19 is higher.  At this time, there is no clear evidence suggesting the variant causes more severe disease.

Beta variant: Early modelling studies show that this strain is more transmissible than strains that circulated during the first wave of the pandemic.  At this time, not enough data is available to determine the severity of this variant.

Gamma variant: Little is known about the transmissibility of this variant; however, it contains the same mutation associated with increased transmissibility as the other two VOCs.  There has been one confirmed case of reinfection with the P.1 variant, and some studies suggest that it may be able to infect people who have received the vaccine.   At this time, little is known about the severity of this variant.

Delta variant: Studies indicate that the Delta variant is 50% more transmissible than the Alpha variant.  Receiving the second dose will be key in protecting against severe disease outcomes.

How are cases with variants identified?

Analyses of all positive COVID-19 test results are conducted by the Public Health Ontario Laboratory.  All positive COVID-19 cases are screened for a mutation that is shared by the VOCs.  This process can take 1-2 days.  If the specimen screens positive for a VOC, we are alerted while the Public Health Lab conducts genomic sequencing of the virus to determine the precise strain.  Genomic sequencing can take up to 14 days.  The Public Health lab also test results for other variants that may be emerging.  This is just one more reason why getting tested when you have symptoms is so important.

How do we stop the spread of variants?

The layering of all public health measures together will be the most effective in reducing the spread of variants.  This means everyone needs to wear their masks, maintain a minimum of 2-metres of physical distance from others, wash their hands frequently, and keep close contacts to household members only.  Residents are asked to restrict non-essential travel, especially outside of Peterborough City and County.  If you are unable to wear a mask, PPH recommends engaging in online ordering and delivery services.  If you suspect you have been in contact with a case of COVID-19, or if you are experiencing any symptoms, seek testing and isolate until you receive your test results and associated instructions.

How many variant cases are in Ontario right now?

As of February 22, 2021, Ontario is reporting a total of 390 cases of variant B.1.1.7, 9 cases of variant B.1.351, and 1 case of variant P.1.  For up-to-date information on the number of cases per variant, please check out the daily summary of cases in Ontario.

What is the difference between presumed and confirmed VOC cases on the Local COVID Tracker?

Positive COVID-19 cases are screened for a mutation that all the variants share.  The screening can take up to 1-2 days.  If the test screens positive for the mutation, we count it as a presumed VOC on our tracker.  To determine the precise VOC the Ontario Public Health Labs conduct genomic sequencing.  The sequencing can take 7-14 days.  Once we receive confirmation on the specific strain, then that case is officially listed as confirmed case of VOC on our tracker.

What is PPH doing to protect against variants?

PPH is closely watching for variants locally, and is currently working with local partners to ramp up vaccinations of high-risk populations.  PPH is also implementing the provincial guidance for strengthening measures we know work, including identifying high risk contacts and more intense outbreak management if a variant does occur in a high-risk setting, such as a school or workplace.

How do we protect ourselves against variants?

Continue to follow public health guidelines including handwashing, sanitizing high touch surfaces, physical distancing, wearing a mask, and staying home as much as possible.  Do not have close contacts outside your household, unless for essential purposes like providing child care.  Do not travel outside of the Peterborough region, unless it is essential.  If you believe that you have come in contact with someone with COVID-19, or if you have symptoms of COIVD-19 please get tested and isolate.  Testing is the best way to detect any variants of concern.  Continue to isolate until you receive your test results and associated instructions.