COVID-19 Variants of Concern and Canada’s Immunization Efforts

Fact Sheet

February 18, 2021

Summary: A number of new COVID-19 variants of concern have recently been identified in Canada  during 2021, leading to concerns about increased transmissibility, potentially worsened disease severity  and resistance to existing vaccines. 

How immunity after vaccination works: The immunity to the coronavirus we develop following  vaccination or infection is largely due to the development of antibodies that bind to the receptor binding domain (RBD).1 

How the current vaccines (Pfizer-BioNTech and Moderna) approved in Canada work to protect people: Pfizer-BioNTech and Moderna are both mRNA vaccines. mRNA vaccines work by introducing an mRNA  sequence (the molecule which tells cells what to build) which is coded for a disease-specific antigen; once produced within the body, the antigen is recognised by the immune system, preparing it to fight  the real thing. 

Mutations of concern in new variants 

N501Y: Using the spike protein is how the coronavirus enters cells, and N501Y is in an especially  important region called the receptor-binding domain, which latches on to the cell. An N501Y mutation  may make the spike protein stickier, allowing it to bind to and enter cells more readily. 

D614G: The D614G strain of coronavirus dominates because it increases the spike protein’s ability to  open cells for the virus to enter. The D614G mutation causes a flap on the tip of one spike to pop open,  allowing the virus to infect cells more efficiently. 

E484K escape mutation: Mutations in the spike domain of the virus can allow the virus to evade or  partially evade these antibodies. This is the reason they are called “escape mutations”.  

Current status: 570 cases of variants have been confirmed in Canada (February 17, 2021). 

1 Receptor-binding domain (RBD) is a key part of a virus located on its spike domain that allows the virus to dock to  body receptors and gain entry into cells, leading to infection. 

B117 (UK/Kent variant) 

• First detected in September 2020 in Greater London UK region. 

• First detected in December in Ontario; now found in all Canadian provinces, most in Ontario; 300 cases in Newfoundland and Labrador have been associated with this variant. Community spread of B117 has been confirmed in at least four provinces. It is predicted to become the dominant variant sometime in March. 

• Transmissibility rate: averages 50% (CDC) 

• Why it spreads 

o One analysis found that more than a third of patients infected by B117 had high viral loads. o N501Y: Because of the N501Y mutation, B117 strain may also be ‘stickier’, or better able to  grab onto the cells that it infects. 

o D614G: Allows B117 to enter cells more effectively, giving it the ability to spread more  quickly than the original predominant virus. 

• Risk of severe illness: In January 2021, scientists from the UK reported evidence that suggests the  B117 variant may be associated with an increased risk of death, compared with other variants. According to UK researchers, it is estimated to be 30% more fatal. 

• Vaccine efficacy: Because B117 and the most prevalent strain share 99% of the same proteins, it is  likely that both the Moderna and Pfizer-BioNTech vaccines will still be effective against the variant. 

B117 with E484K mutation 

• On February 1, 2021, scientists in the United Kingdom reported that a small number of B117  variants have developed the E484K mutation thought to help SARS-CoV-2 partly evade immunity. 

501Y.V2, or B.1.351 (South African variant) 

• First detected in October 2020 in Nelson Mandela Bay, South Africa 

• Detected first in Alberta in January 2021, now in Ontario, Quebec and British Columbia  • Based on the UK variant 

• Transmissibility rate: 50% 

• Why it spreads 

o N501Y: Because of the N501Y mutation, the strain may also be ‘stickier’, or better able to  grab onto the cells that it infects. 

o D614G: Allows B.1.351 to enter cells more effectively, giving it the ability to spread more  quickly than the original predominant virus. 

• Risk of severe illness: Currently there is no evidence to suggest that this variant has any impact on  disease severity. 

• Vaccine efficacy:  

o This variant has multiple mutations in the spike protein, including the escape mutation  E484K. 

o A laboratory study suggests that the South African variant of the coronavirus may reduce  antibody protection from the Pfizer/BioNTech vaccine by two -thirds, and it is not clear if the  shot will be effective against the mutation, the companies have said. The study found the  vaccine was still able to neutralise the virus, and there is not yet evidence from trials in  people that the variant reduces vaccine protection, particularly against severe illness. The  company is making investments and talking to regulators about developing an updated  version of their mRNA vaccine, or a booster shot, if needed. 

P.1 (Brazilian variant) 

• First identified in January 2021 in travelers from Brazil who arrived in Japan • Detected in Ontario only (one case) 

• Based on the UK variant 

• Transmissibility rate: unknown 

• Why it spreads 

o N501Y: Because of the N501Y mutation may also be ‘stickier’, or better able to grab onto  the cells that it infects. 

o D614G: Allows P.1 to enter cells more effectively, giving it the ability to spread more quickly  than the original predominant virus. 

• Risk of severe illness: Currently there is no evidence to suggest that this variant has any impact on  disease severity. 

• Vaccine efficacy: unknown 

o The P.1 variant has 17 unique mutations, including three in the receptor-binding domain of  the spike protein, and including the escape mutation E484K. 

B1525 (Nigerian variant) 

• 1 case found in British Columbia 

• Includes the escape mutation E484K 

Will the existing vaccines work? Evidence suggests that the available COVID-19 vaccines may still  produce protective immune response against the new variants identified even when the escape mutation is present. Changes to the vaccine can be made to target novel variants and will likely be  needed as new variants will begin to become dominant amongst the viruses that are circulating. 

Strategies have been devised to overcome a potential decrease in vaccine efficacy: • The vaccine administration regimen can be modified to increase the overall immune response  and, ideally, provide more protection against new variants (e.g., an additional booster vaccine  dose can be considered). 

• Optimisation of the original vaccine, such as the development of a new version with an  updated spike protein, is also possible. 

• To determine whether either of these approaches are required, surveillance data on emerging  variants are being collected to ensure that the best vaccine strategy is being employed. • As new variants continue to spread, it is more important than ever that existing public health  measures – masking, physical distancing, hand washing, cleaning protocols and ventilation – be  maintained and even potentially enhanced, even as the vaccine rollout continues across  Canada.  

References 

Zhang, Z. (2021, January 18). The Atlantic. 

https://www.theatlantic.com/health/archive/2021/01/coronavirus-evolving-same-mutations-around world/617721/ 

CDC: 

• https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/scientific-brief emerging-variants.html 

• https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/variant-surveillance/variant info.html 

Zimmer, K. (2021, January 26). The Scientist Magazine. A Guide to Emerging SARS-CoV-2 Variants | The  Scientist Magazine® (the-scientist.com) 

Technology Networks. (2020, November 13). Genomics Research from Technology. https://www.technologynetworks.com/genomics/news/what-the-d614g-mutation-means-for-sars-cov 2-vaccines-342786 

Duong, D. (2021, January 25). CMAJ. https://www.cmaj.ca/content/193/4/E141 

Astrazeneca: 

https://www.astrazeneca.com/what-science-can-do/topics/disease-understanding/the-natural evolution-of-sars-cov-2.html