| Those at high risk of severe illness and death from COVID-19:
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There are large or important independent associations of severe COVID-19 outcomes with increasing age and for certain high-risk health conditions.19 There is moderate certainty of evidence for a very large or very important association of hospital admission and death, particularly in those older than 70 years (v. age ≤ 45 yr) and low certainty of evidence for a large or important association of hospital admission or death with certain high-risk conditions (Table 1).19 Studies treating age on a continuum or across small increments consistently found that risks for hospital admission and death increase with increasing age (e.g., about 2%–6% and 5%–10% relative increase in risk per year, respectively).19 Current surveillance data in Canada have shown that hospital admission, ICU admission and death rates from COVID-19 increase with age, and that people with certain underlying health conditions are at highest risk of developing more severe illness from COVID-19.20 Expert stakeholder groups and patient and community advocates,21 as well as the Canadian public,13 rank the relative importance of an immunization strategy to protect those who are most vulnerable to severe illness and death from COVID-19 as first in the context of limited vaccine supply. Most Canadians identified those with underlying medical conditions (57%) and older people (53%) as groups who should get a SARS-CoV-2 vaccine first, if supplies are limited.12 When provided with a list of specific groups to be prioritized to receive the vaccine, 19% ranked those with high-risk medical conditions and 12% ranked older adults as the top priority.13 Older Canadians are significantly more willing than younger Canadians to get an effective recommended SARS-CoV-2 vaccine,12,13,15 and those 35 years and older with a “serious long-term illness” are somewhat more willing to get an effective recommended SARS-CoV-2 vaccine.12,13
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Those most likely to transmit COVID-19 to those at high risk of severe illness and death from COVID-19 and workers essential to maintaining the COVID-19 response
Health care workers, personal care workers and caregivers providing care in long-term care facilities or other congregate care facilities for seniors Other workers most essential in managing the COVID-19 response or providing front-line care for patients with COVID-19 Household contacts of those at high risk of severe illness and death from COVID-19
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In Canada, long-term care facilities have experienced a large number of outbreaks associated with a high number of fatalities.20 Immunizing health care, personal care and other workers providing front-line care directly protects them from acquiring SARS-CoV-2 infection and could indirectly protect their patients and health care capacity. Although front-line health care workers and other workers functioning in a health care capacity (e.g., providing medical first response) have differential exposure to SARS-CoV-2 with potential transmission to high-risk individuals, they may have more access to and training in the use of PPE and other infection prevention and control measures, and so exposure risk could be substantially reduced compared with other groups. Protection against infection with SARS-CoV-2 has been demonstrated in health care workers with the use of PPE.22,23 Immunizing health care workers and other workers functioning in a health care capacity minimizes the disproportionate burden of those taking on additional risks to protect the public. Absenteeism because of illness or perceived risk of illness from COVID-19 among health care workers and other workers most essential in managing the COVID-19 response (e.g., outbreak management, laboratory testing, immunization) may compromise health care capacity and the management of the COVID-19 response. Expert stakeholder groups and patient and community advocates,21 as well as the Canadian public,13 rank the relative importance of an immunization strategy to protect health care capacity as second priority, and an immunization strategy to minimize transmission of COVID-19 as third in the context of limited vaccine supply. 22% of Canadians identify “health care workers” as a key population for priority immunization in the case of SARS-CoV-2 vaccine shortage.12 When provided with a list of specific groups to be prioritized to receive the vaccine, “health care workers” was the group most commonly ranked first by most Canadian respondents (40%).13 Immunizing those able to transmit SARS-CoV-2 to those at high risk of severe illness and death could indirectly protect those at high risk (if the vaccine is effective in interrupting transmission), which could be particularly important if vaccine characteristics are not favourable in high-risk populations.
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| Those contributing to the maintenance of other essential services for the functioning of society (to be defined, prioritized and informed by ongoing federal, provincial and territorial discussions) |
Certain individuals who cannot work virtually may have differential exposure to SARS-CoV-2. Designations of essential services in the context of the COVID-19 pandemic vary across jurisdictions in Canada. Guidance on essential services and functions during the COVID-19 pandemic, including lists published by provinces and territories, is available.24 Provinces and territories have expressed a desire for a harmonized approach to vaccine prioritization for essential services. The appropriate federal, provincial and territorial health tables will be consulted in discussions on prioritization for the purposes of immunization. Immunizing this population minimizes the disproportionate burden of those taking on additional risks to maintain services essential for the functioning of society. Absenteeism because of illness or perceived risk of illness from COVID-19 among some workers who cannot work virtually may compromise essential services. Expert stakeholder groups and patient and community advocates,21 as well as the Canadian public,13 rank the relative importance of an immunization strategy to protect critical infrastructure as fourth in the context of limited vaccine supply. 18% of Canadians identify “front-line or essential workers” as a key population for priority immunization in the case of SARS-CoV-2 vaccine shortage.12
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| Those whose living or working conditions put them at elevated risk of infection and where infection could have disproportionate consequences, including Indigenous communities (to be defined based on COVID-19 epidemiology and evidence from previous pandemics) |
In Canada, a high number of COVID-19 outbreaks or clusters in institutions (e.g., correctional facilities), work settings (e.g., agricultural or meat production or packing facilities) and congregate-living settings (e.g., shelters, migrant workers) have occurred.20 The risk of transmission is high in these settings, where physical distancing and other infection prevention and control measures are challenging, and individuals may not be able to exercise sufficient personal actions to adequately protect themselves from infection. This increased risk may expand to other settings as they reopen. Remote or isolated populations or those in some congregate-living populations may not have ready access to sufficient health care infrastructure. Therefore, their risk for death and societal disruption is proportionally greater, as the response to any illness within the community might be suboptimal. Indigenous communities have been disproportionately affected by past pandemics (e.g., the 2009 H1N1 influenza pandemic) and require special consideration of issues related to equity, feasibility and acceptability.
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