COVID-19 vaccines: Canadian Immunization Guide

For health professionals

Notice

This chapter has not yet been updated with the following statements from the National Advisory Committee on Immunization (NACI):

Last partial content update: December 15, 2023

This chapter was updated to further reflect the authorization of Novavax Nuvaxovid XBB.1.5 vaccine.

This information is captured in the table of updates.

On this page

Key information (refer to text and tables for details)

What

Who

How

Why

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Epidemiology

Disease description

Infectious agent

COVID-19 is caused by the SARS-CoV-2 virus, which was first recognized in Wuhan, China in December 2019.

Transmission

Current evidence suggests that SARS-CoV-2 is spread through respiratory droplets and aerosols created when an infected person breathes, coughs, sneezes, sings, shouts, or talks. A person may be infectious for up to 2 to 3 days before showing symptoms and most people are considered no longer infectious 10 days from onset of symptoms (or first detection of infection if asymptomatic), although some may be infectious for longer.

More information on the transmission of SARS-CoV-2 can be found on the Public Health Agency of Canada (PHAC) webpages for COVID-19: Main modes of transmission.

Variants of concern

Genetic mutations in the SARS-CoV-2 virus have led to the designation of variants of concern (VOCs). Such mutations may lead to changes in transmissibility, severity of disease or the level of protection offered by vaccines or previous infection. Since late December 2021, Omicron has been the predominantly circulating VOC with a variety of sub-lineages emerging.

More information on the VOCs reported in Canada is available in the COVID-19 epidemiology update. The COVID-19 Weekly Epidemiological Update by the World Health Organization (WHO) provides a summary on the global distribution and emerging evidence on VOC and variants of interest (VOI). Differences between VOC and VOI are available from SARS-CoV-2 variants: National definitions, classifications and public health actions.

Risk factors

Anyone can be infected with SARS-CoV-2. However, some populations are at increased risk of exposure to the virus (e.g., due to living or occupational settings), and some populations are at increased risk of severe disease and outcomes (e.g., hospitalization and death) due to biological factors (e.g., advanced age, pre-existing medical conditions, pregnancy) and social factors (e.g., socioeconomic status, belonging to a racialized population). Exposure and risk factors for severe disease may overlap, further increasing risk. Any combination of these factors, as well as varying access to health care services, has the potential for disproportionate consequences for specific populations characterized by increased rates of infection and disease, severe illness, hospitalizations, and/or deaths.

There is a spectrum of COVID-19 disease severity, ranging from asymptomatic to mild, moderate, severe and critical disease. Severe disease more often occurs in those with increasing age and those with underlying medical conditions, with the risk increasing with the number of underlying conditions. A list of underlying medical conditions associated with more severe COVID-19 disease can be found in COVID-19 signs, symptoms and severity of disease: A clinician guide.

There is limited evidence on clinical risk factors for severe COVID-19 disease in pediatric populations. Children at increased risk for severe outcomes may include children who are medically fragile/have medical complexities, children with more than one comorbidity, children with neurological disorders, children with chronic lung disease, and children with Down syndrome (Trisomy 21) and other immunocompromising conditions.

Spectrum of clinical illness and disease characteristics

The median incubation period (the time from exposure to symptom onset) for non-variant SARS-CoV-2 was estimated to be 4 to 7 days. For Omicron, the median incubation period is 2 to 4 days. The incubation period can range from 2 to 14 days.

Clinical presentation and symptoms of COVID-19 vary in frequency and severity, from asymptomatic to severe and fatal disease. To date, there is no list of symptoms that has been validated to have high specificity or sensitivity for COVID-19.

More information on the spectrum of clinical illness is available on the PHAC webpage for COVID-19 signs, symptoms and severity of disease: A clinician guide.

While most children and adolescents with COVID-19 have mild or no symptoms, some do experience severe disease. However, children and adolescents report fewer severe outcomes of COVID-19 (i.e., hospitalizations due to COVID-19, ICU admission, and deaths) compared to older age groups.

Children, adolescents and adults with SARS-CoV-2 infection are at risk of multisystem inflammatory syndrome (MIS), a rare but serious condition that can occur several weeks following SARS-CoV-2 infection. They are also at risk of post COVID-19 condition (PCC), a condition in which symptoms persist for more than 8 weeks and are present 12 or more weeks following acute infection with SARS-CoV-2. Refer to Effectiveness of vaccination against post-COVID-19 condition.

Disease incidence

Global

Updated international data on COVID-19 cases and deaths are available.

Weekly epidemiological updates highlighting key global, regional and country-level data on COVID-19 cases and deaths are available from WHO.

National

Updated national, provincial and territorial-level data on COVID-19 cases and deaths in Canada over time is available from the PHAC webpage on COVID-19 epidemiology update: Summary.

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Preparations authorized for use in Canada

There are some preparations of mRNA COVID-19 vaccines that are no longer available but still authorized for use. These are listed in the chapter Contents of immunizing agents authorized for use in Canada.

XBB.1.5 vaccines are now the recommended product of choice.

mRNA vaccines

COVID-19 vaccines that use mRNA platforms contain mRNA with modified nucleosides that code for the SARS-CoV-2 spike protein. The mRNA can encode for the spike protein from the original SARS-CoV-2 virus or from a variant of concern. The currently recommended mRNA vaccines code for the Omicron XBB.1.5 sub-lineage. A lipid nanoparticle formulation delivers the mRNA into the recipient's cells. Once inside the cytoplasm of a cell, the mRNA provides instructions to the cell's protein production machinery to produce the trans-membrane spike protein antigen that becomes anchored on the cell's external surface. The mRNA does not enter the nucleus of the cell and does not interact with, or alter, human DNA. The immune system is engaged by both the transmembrane spike protein and immune receptors carrying spike antigens to induce humoral and cellular immune responses. The mRNA, lipid nanoparticle, and spike protein are degraded or excreted within days to weeks from time of immunization. mRNA vaccines are not live vaccines and cannot cause infection in the host.

Protein subunit vaccine

The protein subunit vaccine consists of a purified full-length SARS-CoV-2 recombinant spike protein nanoparticle co-formulated with the adjuvant Matrix-M. Matrix-M is a novel saponin-based adjuvant that facilitates activation of the cells of the innate immune system, which enhances the magnitude of the spike protein-specific immune response.

Viral vector (non-replicating) vaccines

Two viral vector vaccines had been authorized for use in Canada for adults 18 years of age and older; Vaxzevria™ (ChAdOx1-S recombinant) from AstraZeneca Canada (along with the version manufactured by the Serum Institute of India and marketed briefly in Canada as COVISHIELD) and Jcovden COVID-19 vaccine (Ad26.COV2.S) from Janssen Inc. They are no longer available in Canada.

Anti-SARS-CoV-2 monoclonal antibodies authorized for pre-exposure prophylaxis of COVID-19

Tixagevimab and cilgavimab are two recombinant human monoclonal antibodies with amino acid substitutions to extend antibody half-life and thus duration of protection, as well as minimize the potential risk of antibody-dependent enhancement of disease. In addition to authorization for pre-exposure prophylaxis, Evusheld has also been authorized to treat mild to moderate COVID-19.

Up-to-date information on alerts, including risk of treatment failure of specific anti-SARS-CoV-2 monoclonal antibodies as well as safety and recalls, is available from Health Canada. Refer to the product monograph for updates on the neutralization of recent variants and risk of treatment failure.

For complete prescribing information for any of the Preparations authorized for use in Canada, consult the product leaflet or information contained within Health Canada's authorized product monographs available through the Drug Product Database.

Refer to Contents of immunizing agents authorized for use in Canada in Part 1 for lists of vaccines and passive immunizing agents authorized for use in Canada and their contents.

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Immunogenicity, efficacy and effectiveness

Immunogenicity

All COVID-19 vaccines induce humoral immune responses, including binding and neutralizing antibody responses, and have been shown to produce cellular immune responses in adult populations. The immune responses may vary depending on the product used, number of doses, interval between the doses (longer intervals result in higher antibody titres), the strains against which the immune response is assessed and how immunologically similar the strain is to the vaccine strain, and the age and underlying medical conditions of the vaccine recipient (antibody titres may be lower in older adults and those who are immunocompromised due to disease or medication). Antibody titres decrease over time since vaccination, although memory responses that can be boosted with vaccination or infection persist.

Antibody titres tend to be higher with vaccines that are antigenically closer to the strain that they are tested against. Clinical studies have shown that bivalent (Omicron BA.4/5 strains) vaccines have lower responses against more recently circulating strains derived from Omicron XBB, than against previously circulating Omicron BA.5. Based on pre-clinical studies, the XBB.1.5 vaccine produces higher antibody titres against strains derived from XBB than the bivalent (Omicron BA.4/5) vaccine.

No immunological correlate of protection has been determined for SARS-CoV-2, and therefore the implications of differences in immune responses after COVID-19 vaccination on protection against infection and severe disease, as well as on duration of protection, is uncertain.

Efficacy and effectiveness

Efficacy (how well the vaccine works in clinical trials) and effectiveness (how well the vaccine works in real-world observational studies) of COVID-19 vaccines tends to be lowest against infection, somewhat higher against symptomatic disease and highest against severe disease.

Similar to factors that impact the immune response, vaccine effectiveness may be affected by the vaccine product received, the interval between doses (somewhat better with longer intervals), the time since the most recent dose (as immunity wanes), the circulating strains and the age and health status of the recipient and their prior SARS-CoV-2 infection history.

Initial randomized clinical trials using original monovalent vaccines demonstrated high efficacy (over 90%) in adults against symptomatic and severe disease caused by early SARS-CoV-2 strains for both mRNA vaccines (Pfizer-BioNTech Comirnaty and Moderna Spikevax) and the adjuvanted subunit vaccine (Novavax Nuvaxovid).

Studies have also demonstrated efficacy against symptomatic disease of original monovalent vaccines in children, but efficacy was somewhat lower, noting that studies were done later when variants were circulating. Efficacy against severe disease in children 6 months to 4 or 5 years of age could not be assessed because this outcome was rare. Observational studies have also shown protection against hospitalization due to multisystem inflammatory syndrome in children 5 to 18 years of age.

Vaccine protection decreases over time, particularly against infection and symptomatic disease, and to a lesser extent against severe disease as well. Subsequent doses in those previously vaccinated (i.e., booster doses) are intended to increase protection, particularly against severe disease, that may have decreased over time.

Bivalent (Omicron BA.1 or BA.4/5 strain) vaccines enhanced protection against infection/symptomatic disease and severe disease that had waned over time from previous monovalent original vaccines in the context of earlier Omicrons strains such as BA.4/5. The protection offered by bivalent vaccines was similar or somewhat greater than protection offered by original monovalent vaccines against disease due to Omicron. Vaccine effectiveness with the XBB.1.5 formulations in the context of circulating strains will be monitored as usage increases since these vaccines became available in the fall of 2023, however individuals vaccinated with the updated vaccine are expected to benefit from a greater immune response against currently circulating strains compared to earlier formulations.

Protection is higher in those with previous SARS-CoV-2 infection and vaccination (hybrid immunity) than in those who have only been vaccinated or only been infected. A recent Omicron sub-lineage infection combined with COVID-19 vaccination provides the highest degree of protection against future Omicron sub-lineage infection and severe disease.

Vaccine effectiveness against transmission is also measured in some studies. To the extent that COVID-19 vaccines protect against infection, they also prevent transmission as those who are not infected cannot spread infection to others. In addition, vaccination may offer additional protection against transmission even if infection is not prevented as it may reduce viral load and duration of infection. This has previously been demonstrated particularly with a booster dose, although the duration of this protection against transmission remains uncertain and the impact on transmission against currently circulating strains is unknown.

Effectiveness of vaccination against post-COVID-19 condition

Post COVID-19 condition (PCC) is a condition in which symptoms following a SARS-CoV-2 infection persist for more than 8 weeks and are present for 12 or more weeks following the acute phase. The predominant symptoms experienced with PCC include fatigue, dyspnea, other respiratory issues, cardiovascular issues, pain, sleep disturbances, decrease in quality of life, cognitive impairment, and anxiety or depression. PCC has been estimated to affect approximately 10 to 20% of individuals following COVID-19.

Evidence suggests that receipt of 2 doses of COVID-19 vaccine prior to infection decreases the odds of PCC after SARS-CoV-2 infection compared to those who are unvaccinated. There is low confidence that one dose of COVID-19 vaccine prior to infection will decrease the odds of PCC after infection while the impact of a third dose prior to infection is currently uncertain. Whether vaccination following SARS-CoV-2 infection can decrease the risk of PCC remains to be established. Research has not demonstrated a worsening of existing PCC symptoms with vaccination, and appears to be safe. It is unclear if vaccination may improve established PCC symptoms.

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Recommendations for use

For the primary series of COVID-19 vaccines:

There is limited evidence on clinical risk factors for severe COVID-19 disease in pediatric populations. Children at increased risk for severe outcomes may include children who are medically fragile/have medical complexities, children with more than one comorbidity, children with neurological disorders, children with chronic lung disease, and children with Down syndrome (Trisomy 21), and other immunocompromising conditions.

See Schedule for the primary series section for additional information.

For those previously vaccinated, COVID-19 vaccination is recommended for the above groups and is particularly important for those at increased risk of SARS-CoV-2 infection or severe COVID-19 disease as follows:

Autonomous decisions should be made by Indigenous Peoples with the support of healthcare and public health partners in accordance with the United Nations Declaration on the Rights of Indigenous Peoples Act.

XBB.1.5 vaccines are the currently recommended products for both the primary series (whether starting or completing the series) and for those previously vaccinated.

Schedule for the primary series

Children 6 months to under 5 years of age

Two (2) doses of Moderna Spikevax XBB.1.5 or 3 doses of Pfizer-BioNTech Comirnaty XBB.1.5 are recommended, with an 8-week interval between doses. An additional dose is recommended for individuals who are moderately to severely immunocompromised, with an interval of 4 to 8 weeks between each dose (see Table 1 for schedules and dosages).

The 8-week interval is longer than the authorized interval and is recommended as a better immune response has been associated with a longer interval between doses. For those who are moderately to severely immunocompromised, the 4 to 8-week interval between doses needs to balance a potentially better immune response with longer intervals with the need for earlier protection due to risk of exposure from circulating SARS-CoV-2 and the risk of severe COVID-19 disease.

Those who are moderately to severely immunocompromised are recommended to receive an additional dose in the primary series compared to those who are not immunocompromised in order to help improve the immune response and vaccine effectiveness in this group (based on data from adults). Those who are moderately to severely immunocompromised generally respond less well to COVID-19 vaccines and are at higher risk for severe illness.

If children 6 months to under 5 years of age started the primary series with a non-XBB.1.5 vaccine (i.e., original monovalent, BA.1 bivalent or BA.4/5 bivalent) but did not complete the series, they should complete the primary series with an XBB.1.5 vaccine (see Table 2).

For children 6 months to under 5 years of age who are moderately to severely immunocompromised, a 3-dose series of the Moderna Spikevax (25 mcg) vaccine is preferred over 4 doses of Pfizer-BioNTech Comirnaty (3 mcg) because there is likely higher acceptability and more feasible implementation due to fewer doses in the schedule using Moderna Spikevax.

A mixed product schedule using vaccines from different manufacturers can be offered for the primary series, however if both Pfizer-BioNTech Comirnaty and Moderna Spikevax vaccine products are used in the same primary series for an individual 6 months to under 5 years of age, the total number of doses in the series should follow the Pfizer-BioNTech Comirnaty schedule (see Table 2).

Children who started the primary series with a non-XBB.1.5 vaccine at less than 5 years of age and turn 5 years of age before completing the series, should receive the number of XBB.1.5 vaccine doses recommended as per Table 2 for those 5 years of age and older (including relevant footnotes). Children who started a primary series with an XBB.1.5 vaccine at less than 5 years of age and turn 5 years of age before completing the primary series, should receive the following with the age-appropriate dosage for their current age:

Individuals 5 years of age and over

One dose of XBB.1.5 vaccine is recommended as per the authorized schedule in the product monograph. An additional dose is recommended for individuals who are moderately to severely immunocompromised, with an interval of 4 to 8 weeks between the two doses (see Table 1 for schedules and dosages).

Those who are moderately to severely immunocompromised are recommended to receive an additional dose in the primary series compared to those who are not immunocompromised in order to help improve the immune response and vaccine effectiveness in this group. Those who are moderately to severely immunocompromised generally respond less well to COVID-19 vaccines and are at higher risk for severe illness.

The 4 to 8-week interval for those who are moderately to severely immunocompromised needs to balance a potentially better immune response with the longer interval with the need for earlier protection due to risk of exposure from circulating SARS-CoV-2 and the risk of severe disease. As well, the risk of myocarditis/pericarditis following the second dose has been determined to be lower with longer intervals between doses.

If a person 5 years of age and over started the primary series with a non-XBB.1.5 vaccine (i.e., original monovalent, BA.1 bivalent or BA.4/5 bivalent) but did not complete the series, they should complete the primary series with an XBB.1.5 vaccine based on the total number doses previously recommended (i.e., they should receive a total of 2 COVID-19 vaccine doses in the primary series if not immunocompromised and 3 doses in the primary series if they are immunocompromised) (see Table 2).

For children who started a primary series at less than 5 years of age and turn 5 years of age before completing the primary series, see guidance above for Children 6 months to under 5 years of age.

There is no longer a product preference between Moderna Spikevax and Pfizer-BioNTech Comirnaty with the use of XBB.1.5 COVID-19 vaccines for unvaccinated individuals 12 to 29 years of age. Previously, Pfizer-BioNTech Comirnaty had been preferred over Moderna Spikevax for the primary series among individuals 12 and 29 years of age due to the higher risk of myocarditis/pericarditis observed following the Moderna Spikevax 100 mcg original monovalent vaccine primary series (especially after the second dose). This product preference has now been removed. As compared to the original monovalent primary series, the risk of myocarditis/pericarditis is now expected to be lower due to the use of a 1-dose schedule in most individuals and potentially due to a lower dosage of the available Moderna Spikevax vaccine (50 mcg in the XBB.1.5 formulation compared to 100 mcg in the original monovalent formulation).

mRNA vaccines are the preferred products. It is recommended that a primary series of the authorized protein subunit COVID-19 vaccine (Novavax Nuvaxovid XBB.1.5) should be offered to those 12 year of age and older who are not able or willing to receive an mRNA COVID-19 vaccine. Preference of mRNA vaccines over the protein subunit vaccine is due to the availability of more data with regard to the benefits and risks of mRNA vaccines compared to the protein subunit vaccine. Recommendations regarding the use of the protein subunit vaccine are currently under review by NACI. Both the original mRNA vaccines and Novavax Nuvaxovid original have been associated with a rare risk of myocarditis/pericarditis. Data is not yet available for XBB.1.5 vaccines.

When offering Novavax Nuvaxovid XBB.1.5 as a primary series to those 12 years of age and older who are moderately to severely immunocompromised, it should be noted that the safety and efficacy has not been established in these individuals. Informed consent for use of Novavax Nuvaxovid XBB.1.5 for those who are moderately to severely immunocompromised should include the above information, and the well- documented evidence on the safety profile and effectiveness of mRNA COVID-19 vaccines in these populations based on real world use with large numbers of individuals.

Table 1. Immunization schedule for previously unvaccinated individuals by age starting their vaccinations with XBB.1.5 mRNA COVID-19 vaccines
Age group Immunization scheduleFootnote a Products Recommended intervalFootnote b
Schedule for those not moderately or severely immunocompromised
6 months to under 5 years of age
  • 2-dose (Moderna Spikevax) or
  • 3-dose (Pfizer-BioNTech Comirnaty)
  • 25 mcg Moderna Spikevax
  • 3 mcg Pfizer-BioNTech Comirnaty
8 weeks
5 years of age and older
  • 1-dose

Moderna Spikevax

  • 25 mcg (5 to under 12 years)
  • 50 mcg (12 years of age and older)

Pfizer-BioNTech Comirnaty

  • 10 mcg (5 to under 12 years)
  • 30 mcg (12 years of age and older)
Not applicable
Schedule for individuals who are moderately to severely immunocompromised
6 months to under 5 years of age
  • 3-dose (Moderna Spikevax)Footnote c or
  • 4-dose (Pfizer-BioNTech Comirnaty)
As above 4 to 8 weeks
5 years of age and older
  • 2-dose
4 to 8 weeks
a

See Table 2 regarding individuals who started but did not complete a primary series with a vaccine that was not an XBB.1.5 formulation.

Return to footnote a referrer

b

For individuals with recent SARS-CoV-2 infection, these are also the suggested intervals between SARS-COV-2 infection and COVID-19 vaccination.

Return to footnote b referrer

c

Moderna Spikevax is the preferred product in children 6 months to under 5 years of age who are moderately to severely immunocompromised due to acceptability and feasibility considerations of only requiring three doses instead of four doses for Pfizer-BioNTech Comirnaty.

Return to footnote c referrer

For those previously vaccinated

For individuals who have previously been vaccinated with a complete primary series that did not include an XBB.1.5 COVID-19 vaccine, a dose of XBB.1.5 COVID-19 vaccine is recommended 6 months following previous COVID-19 vaccination or SARS-CoV-2 infection (whichever is later). Shorter intervals (i.e., 3 months to less than 6 months) following previous vaccination or infection have also not been shown to pose a safety risk (see Table 2).

Individuals whose primary series includes the XBB.1.5 COVID-19 vaccine do not require further doses at this time once the series is complete.

An mRNA COVID-19 vaccine dose is preferred for those previously vaccinated. However, Novavax Nuvaxovid XBB.1.5 should be offered to individuals 12 years of age and older who are not able or willing to receive an mRNA COVID-19 vaccine. Preference of mRNA vaccines over the protein subunit vaccine is due to the availability of more data with regard to the benefits and risks of mRNA vaccines compared to the protein subunit vaccine. Recommendations regarding the use of the protein subunit vaccine are currently under review by NACI. Both the original mRNA vaccines and Novavax Nuvaxovid original have been associated with a rare risk of myocarditis/pericarditis. Data is not yet available for XBB.1.5 vaccines.

For information on the management of errors and deviations, see PHAC's resource: Quick reference guide on the use of COVID-19 vaccines: Managing vaccine administration errors or deviations for additional guidance.

Table 2. Summary of number of recommended XBB.1.5 mRNA COVID-19 vaccine doses based on previous non-XBB.1.5 vaccination history (i.e., previously received original monovalent or BA.1 bivalent or BA.4/5 bivalent vaccines (non-XBB.1.5)Footnote a

Age

Previous vaccination with only non-XBB.1.5 mRNA COVID-19 vaccines

Number of doses and interval of XBB.1.5 mRNA COVID-19 vaccines to be administered

Moderna Spikevax XBB.1.5 scheduleFootnote b

Pfizer-BioNTech Comirnaty Omicron XBB.1.5 scheduleFootnote c

For those not moderately to severely immunocompromised

6 months to under 5 yearsFootnote d 3 or more doses See 2 or more doses

1 dose

6 months from last dose

Shorter intervals (i.e., 3 months to less than 6 months) have also not been shown to pose a safety risk

2 or more doses

1 dose

6 months from last dose

Shorter intervals (i.e., 3 months to less than 6 months) have also not been shown to pose a safety risk

See 2 doses or 3 or more doses, as applicable
2 doses

See 2 or more doses

1 dose

8 weeks from last dose

1 dose

1 dose

8 weeks from last dose

2 doses

8 weeks from last dose and between doses

5 years of age and older 2 or more doses

1 dose

6 months from last dose

Shorter intervals (i.e., 3 months to less than 6 months) have also not been shown to pose a safety risk

1 doseFootnote e

6 months from last dose

Shorter intervals (i.e., 3 months to less than 6 months) have also not been shown to pose a safety risk

1 dose

1 dose

8 weeks from last dose

1 dose

8 weeks from last dose

For those who are moderately to severely immunocompromised
6 months to under 5 yearsFootnote f 4 or more doses See 3 or more doses

1 dose

6 months from last dose

Shorter intervals (i.e., 3 months to less than 6 months) have also not been shown to pose a safety risk

3 or more doses

1 dose

6 months from last dose

Shorter intervals (i.e., 3 months to less than 6 months) have also not been shown to pose a safety risk

See 3 doses or 4 or more doses, as applicable
3 doses

See 3 or more doses

1 dose

4 to 8 weeks from last dose

2 doses

1 dose

4 to 8 weeks from last dose

Moderna is preferredFootnote f

2 doses

4 to 8 weeks from last dose and between doses

1 dose

2 doses

4 to 8 weeks from last dose and between doses

Moderna is preferredFootnote f

3 doses

4 to 8 weeks from last dose and between doses

5 years of age and olderFootnote h 3 or more doses

1 dose

6 months from last dose

Shorter intervals (i.e., 3 months to less than 6 months) have also not been shown to pose a safety riskFootnote h

1 doseFootnote eFootnote g

6 months from last doseFootnote g

Shorter intervals (i.e., 3 months to less than 6 months) have also not been shown to pose a safety risk

2 doses

1 dose

4 to 8 weeks from last dose

1 doseFootnote g

4 to 8 weeks from last dose

1 dose

2 doses

4 to 8 weeks from last dose and between doses

2 doses

4 to 8 weeks from last dose and between doses

a

Further details on the recommendations on the use of the XBB.1.5-containing COVID-19 vaccines in previously vaccinated individuals are available in the NACI Guidance on the use of COVID-19 vaccines in the fall of 2023 and the subsequent Addendum to the guidance on the use of COVID-19 vaccines in the fall of 2023.

Return to footnote a referrer

b

Note for the primary series for children 6 months to under 5 years of age: Follow this column if all past vaccine doses have been Moderna Spikevax vaccines and now also administering Moderna Spikevax XBB.1.5.

Return to footnote b referrer

c

Note for the primary series for children 6 months to under 5 years of age: Follow this column if now administering Pfizer-BioNTech Comirnaty Omicron XBB.1.5, or if one or more past vaccine doses have been Pfizer-BioNTech Comirnaty vaccines (whether giving Pfizer-BioNTech Comirnaty Omicron XBB.1.5 or Moderna Spikevax XBB.1.5 now).

Return to footnote c referrer

d

Children 6 months to under 5 years of age who are at high risk for severe illness due to COVID-19 should be vaccinated against COVID-19 with a primary series and other children in this age group may be vaccinated.

Return to footnote d referrer

e

Children who are not immunocompromised and started their primary series with 2 doses of a non-XBB.1.5 Pfizer-BioNTech product when they were less than 5 years of age and are completing their primary series at 5 years of age or older, are recommended to receive a total of 3 doses of COVID-19 vaccine in their primary series.

Return to footnote e referrer

f

For those 6 months to under 5 years of age who are moderately to severely immunocompromised, Moderna Spikevax is preferred because it requires only 3 doses, while Pfizer-BioNTech Comirnaty requires 4 doses.

Return to footnote f referrer

g

Children who are moderately to severely immunocompromised and started their primary series with 2 or 3 doses of a non-XBB.1.5 Pfizer-BioNTech product (not the preferred product) when they were less than 5 years of age and are completing their primary series at 5 years of age or older, are recommended to receive a total of 4 doses of COVID-19 vaccine in their primary series.

Return to footnote g referrer

h

If the primary series was started with non-XBB1.5 COVID-19 vaccine(s), those 5 years of age and older who are moderately to severely immunocompromised are recommended to receive a total of 3 doses of COVID-19 vaccines for the primary series.

Return to footnote h referrer

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Vaccination of specific populations

Pregnancy and breastfeeding

Compared to non-pregnant persons, SARS-CoV-2 infection in pregnancy is associated with increased risk of hospitalization and admission to an intensive care unit (ICU). SARS-CoV-2 infection during pregnancy is also associated with an increased risk in the neonate of preterm birth, low birth weight and admission to a neonatal intensive care unit (NICU). Vaccination helps to protect the person who is pregnant and vaccination during pregnancy also lowers the risk of hospitalization for their newborn.

Recommendations

People who are pregnant or breastfeeding are recommended to be vaccinated as per the Recommendation for use section, with COVID-19 vaccination recommended for those 5 years of age and older who have not been previously vaccinated. Pregnancy is included in the group of previously vaccinated individuals for whom COVID-19 vaccination is particularly important.

An mRNA vaccine is preferred due to reassuring published data on the safety of these vaccines in pregnancy. COVID-19 vaccines can be given at any stage of pregnancy.

Considerations

Pregnant or breastfeeding individuals were excluded from COVID-19 vaccine clinical trials. However, analysis of data collected through international COVID-19 immunization registries to date have not revealed any maternal or neonatal safety signals.

Informed consent should include discussion that there is real-world evidence on the safety profile and effectiveness of mRNA vaccination with large numbers of individuals who are pregnant or breastfeeding, but currently limited evidence on the use of the protein subunit vaccine.

Rates of adverse effects are similar in people who are pregnant or breastfeeding and those who are not pregnant or breastfeeding. Studies have not found any impacts of mRNA COVID-19 vaccination on the infant/child being fed human milk or on milk production or excretion. Vaccination during pregnancy does not increase risk for adverse pregnancy/birth outcomes, including miscarriage, stillbirth, low birth weight, preterm birth and NICU admission.

Evidence suggests that COVID-19 mRNA vaccination during pregnancy results in comparable antibody titres to those generated in non-pregnant women. Maternal IgG humoral response to mRNA COVID-19 vaccines transfers across the placenta to the fetus, leading to a significant and potentially protective antibody titre in the neonatal bloodstream 1 week after the second dose. Infants of people who received the second dose of a primary series or a booster dose during pregnancy had a lower risk of hospitalization with COVID-19 (including Omicron) compared to infants born to individuals who were unvaccinated.

The effect was greater with the booster dose than the second dose in a primary series and if the dose was given later in the pregnancy as opposed to earlier. The protection from maternal vaccination against infant hospitalization decreases over time since birth.

Observational studies consistently show that both anti-spike IgG and IgA are present in breastmilk for at least 6 weeks after maternal vaccination with mRNA vaccines. The protection against disease as a result of breastfeeding is currently unknown.

Individuals who have received a COVID-19 vaccine during pregnancy are encouraged to enroll in a COVID-19 vaccine pregnancy registry (see Table 2).

There is a Canadian COVID-19 Vaccine Registry for Pregnant and Lactating Individuals, hosted at the University of British Columbia and supported by the COVID-19 Immunity Task Force (CITF) to assess the safety and effectiveness of COVID-19 vaccines.

Table 3. Pregnancy registry information by vaccine product
Vaccine product Registry information
Pfizer-BioNTech Comirnaty COVID-19 vaccines Pfizer-BioNTech does not have a vaccine registry for pregnant persons. Individuals who are vaccinated with the Pfizer-BioNTech COVID-19 vaccine during pregnancy are encouraged to enroll into the Canadian COVID-19 Vaccine Registry for Pregnant and Lactating Individuals described above.
Moderna Spikevax COVID-19 vaccines There is a vaccine registry that monitors pregnancy outcomes in persons vaccinated with the Moderna COVID-19 vaccine during pregnancy. Individuals who are vaccinated with the Moderna COVID-19 vaccine during pregnancy are encouraged to enroll in the registry by calling 1-866-MODERNA (1-866-663-3762).
Novavax Nuvaxovid COVID-19 vaccines There is a vaccine registry that monitors pregnancy outcomes in persons vaccinated with NUVAXOVID during pregnancy. Individuals who are vaccinated with NUVAXOVID during pregnancy are encouraged to enroll in the registry by visiting C-VIPER: COVID-19 Vaccines International Pregnancy Exposure Registry.

Refer to Immunization in pregnancy and breastfeeding in Part 3 for additional general information.

Individuals previously infected with SARS-CoV-2

The immune response due to prior infection may vary due to factors such as the severity of infection, age, presence of comorbidities, the SARS-CoV-2 variant causing the infection, time since the infection and vaccination history. People with both SARS-CoV-2 infection and COVID-19 vaccination are said to have "hybrid immunity" and have the highest vaccine effectiveness against SARS-CoV-2 infection and severe disease compared to either infection or vaccination alone.

Recommendations

Vaccination is recommended in those who are previously infected as per the Recommendation for use section.

The interval that can be considered from a known SARS-CoV-2 infection to vaccination in the primary series is the same as the recommended intervals between COVID-19 vaccine doses (8 weeks for those who are not immunocompromised, and 4 to 8 weeks for those who are moderately to severely immunocompromised) [see Recommended interval in Table 1]. These suggested intervals serve as a guide and are based on immunological principles and expert opinion and may change as evidence emerges. Clinical discretion is advised for immunizers.

For those who are previously vaccinated, an interval of 6 months is recommended from known SARS-CoV-2 infection to vaccination. Shorter intervals (i.e., 3 months to less than 6 months) following previous vaccination or infection have also not been shown to pose a safety risk.

Individuals with a history of multisystem inflammatory syndrome in children or adults (MIS-C or MIS-A) should wait to be vaccinated for at least 90 days from diagnosis or clinical recovery, whichever is longer.

Safety and efficacy data in individuals previously infected with SARS-CoV-2 and subsequent vaccination with Novavax Nuvaxovid COVID-19 vaccine (for both the original and XBB.1.5 vaccines) are not available.

The following can be considered to define known previous infection with SARS-CoV-2:

Considerations

Testing for previous SARS-CoV-2 infection is not needed prior to COVID-19 vaccination.

Current evidence suggests protection is more robust and longer lasting with vaccination in previously-infected individuals compared to immunity from SARS-CoV-2 infection alone.

A longer interval between infection and vaccination may result in a better immune response from the infection as this allows time for this response to mature in breadth and strength, and for circulating antibodies from the infection to decrease, thus avoiding immune interference when the vaccine is administered.

When considering the suggested intervals outlined above, biological and social risk factors for exposure (e.g., local epidemiology, living settings) and severe disease should also be taken into account.

COVID-19 vaccination in individuals previously infected with SARS-CoV-2 has a good safety profile and is well tolerated. Limited evidence suggests reactogenicity may be slightly increased in individuals previously infected with SARS-CoV-2 compared to those with no history of previous infection, however this evidence is limited to the primary series and variants prior to Omicron.

Immunocompromised persons

Individuals with immunocompromising conditions, including those receiving immunosuppressive therapy, are at increased risk for prolonged infection, serious complications from SARS-CoV-2 infection as well as reduced immune responses to vaccination and reduced vaccine effectiveness. An additional dose in the primary series (compared to the schedule for those who are not immunocompromised) is recommended to help improve the immune response and vaccine effectiveness.

Recommendations

People who are moderately to severely immunocompromised are recommended to be vaccinated as per the Recommendation for use section. Those who are moderately to severely immunocompromised are included in the group of previously vaccinated individuals for whom COVID-19 vaccination is particularly important.

Moderately to severely immunocompromised individuals who are not previously vaccinated should receive a primary series that consists of an additional dose compared to those who are not immunocompromised. The interval between doses in the primary series is recommended to be 4 to 8 weeks. Refer to Schedule for the primary series section for specific recommendations based on age for those who are moderately to severely immunocompromised.

Considerations

Immunocompromised individuals, including those receiving immunosuppressive therapy, are at increased risk for prolonged infection and serious complications from SARS-CoV-2 infection. Numerous studies have shown that immunogenicity is substantially decreased in some immunocompromised individuals when compared to healthy vaccine recipients. Observational studies in adults with complete 1 or 2 dose series, show lower vaccine effectiveness against SARS-CoV-2 infection and COVID-19 disease in immunocompromised adults when compared to the general population.

In considering the 4 to 8-week interval between vaccine doses (or infection and vaccine doses) in the primary series, a longer interval is likely to result in a better immune response. However, moderately to severely immunocompromised individuals (after the initial 1 or 2 doses of the primary series) may still be susceptible during this time before the next dose is administered. If a longer interval between doses is being considered, then the need for earlier protection due to risk of exposure (including local transmission of SARS-CoV-2) and risk of severe disease (e.g., underlying high risk medical condition) should be taken into account. For adolescents and young adults, it should also be noted that the risk of myocarditis/pericarditis is lower with longer intervals between doses.

Indirect data from general adult populations (18 years of age and older) with original mRNA COVID-19 vaccines suggest Moderna Spikevax original (100 mcg) may result in higher vaccine effectiveness after a 2-dose primary series compared to Pfizer-BioNTech Comirnaty original (30 mcg). Moderna Spikevax original (100 mcg) is also associated with a higher seroconversion rate and higher total antibody titres than Pfizer-BioNTech (30 mg) among adult patients who are immunocompromised. It is unknown whether this enhanced immunogenicity would also be observed with Moderna Spikevax XBB.1.5 compared to Pfizer-BioNTech Comirnaty Omicron XBB.1.5 at the different age-based dosages.

A vaccine series should ideally be completed at least 2 weeks before initiation of immunosuppressive therapies where possible.

Moderately to severely immunocompromised includes individuals with the following conditions:

A range of factors can impact the relative degree of immunocompromise and response to COVID-19 vaccines, and clinical and public health judgement should be applied. Jurisdictions may modify the list based on population considerations.

In observational studies and clinical trials, humoral and cellular immune responses were similar between fully vaccinated people living with HIV on antiretroviral therapy and those who were HIV-negative.

Refer to Immunization of immunocompromised persons in Part 3 for a suggested definition of high dose steroids and for guidance on vaccination with COVID-19 vaccines for individuals pre- and post-hematopoietic stem cell transplantation (HSCT) and for chimeric antigen receptor (CAR) T cell therapy recipients.

The safety and efficacy of the protein subunit vaccine has not been established in individuals who are immunocompromised due to disease or treatment. Based on clinical discretion, Novavax Nuvaxovid XBB.1.5 should be offered for moderately to severely immunocompromised individuals in the authorized age group who are not able or willing to receive an mRNA COVID-19 vaccine. Informed consent should include discussion that there is currently limited evidence on the use of the protein subunit vaccine in those who are immunocompromised, while there is evidence on the safety profile and effectiveness of mRNA COVID-19 vaccines based on real world use with large numbers of individuals. Recommendations regarding the use of the protein subunit vaccine are currently under review by NACI, including the schedule for the primary series for those who are moderately to severely immunocompromised.

Based on observational studies, the frequency and severity of adverse events following immunization (AEFI) with an mRNA COVID-19 vaccine in certain immunocompromised populations were comparable to those of non-immunosuppressed individuals. No worsening of underlying disease was reported after immunization.

Refer to Immunization of immunocompromised persons in Part 3 for additional general information.

Travellers

Travellers are recommended to be vaccinated as per the Recommendations for use section.

Travellers who are due for COVID-19 vaccinations should optimally complete these at least 2 weeks before departure. Travellers should verify the travel requirements in place at their destination(s). For more information, refer to the Committee to Advise on Tropical Medicine and Travel (CATMAT) Statement on COVID-19 and International Travel.

Persons new to Canada

Persons new to Canada who are planning to live, work or study in Canada should be vaccinated as per the Recommendations for use section.

Based on a recommendation by PHAC to provinces and territories, people who are planning to live, work or study in Canada who have had only a complete primary series of non-Health Canada authorized vaccines, should be offered an additional dose of an mRNA XBB.1.5 vaccine, unless they have already received 3 doses of a COVID-19 vaccine.

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Serologic testing

Serologic testing is not needed before or after immunization with COVID-19 vaccine.

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Administration practices

Dose and route of administration of available products

The text below summarizes all currently available COVID-19 products. In addition, Table 4 summarizes available XBB.1.5 vaccine products.

Dose

Pfizer-BioNTech Comirnaty Omicron XBB.1.5 COVID-19 vaccine

There are several presentations of Pfizer-BioNTech Comirnaty Omicron XBB.1.5 authorized for use. Only the presentations distributed in Canada are listed below.

Pfizer-BioNTech Comirnaty Omicron XBB.1.5 COVID-19 vaccine (30 mcg)

This presentation has a grey cap and a grey label border and is authorized for use in individuals 12 years of age and older.

No dilution is required.

Each dose is 0.3 mL, containing 30 mcg of SARS-CoV-2 XBB.1.5 spike protein mRNA.

Special precaution should be taken to ensure the correct dose is taken from the multi-dose vial.

Pfizer-BioNTech Comirnaty Omicron XBB.1.5 COVID-19 vaccine (10 mcg, pediatric formulation)

This presentation has a blue vial cap and blue label border and is authorized for use in children 5 to 11 years of age.

No dilution is required.

Each dose is 0.3 mL, containing 10 mcg of SARS-CoV-2 XBB.1.5 spike protein mRNA.

Special precaution should be taken to ensure the correct dose is taken from the multi-dose vial.

Pfizer-BioNTech Comirnaty COVID-19 XBB.1.5 vaccine (3 mcg, pediatric formulation)

This presentation has a maroon vial cap and maroon label border and is authorized for use in children 6 months to 4 years of age.

Dilute with 2.2 mL 0.9% Sodium Chloride Injection, USP, prior to use.

Each dose is 0.2 mL after dilution, containing 3 mcg of SARS-CoV-2 XBB.1.5 spike protein mRNA.

Special precaution should be taken to ensure the correct dose is taken from the multi-dose vial.

Pfizer-BioNTech Comirnaty Original and Omicron BA.4/BA.5 COVID-19 vaccine (Bivalent)

Note that XBB.1.5 vaccines are now the recommended product of choice.

There are two presentations of Pfizer-BioNTech Comirnaty bivalent BA.4/5 vaccine authorized for use.

Moderna Spikevax XBB.1.5 COVID-19 vaccine

There is one presentation of Moderna Spikevax XBB.1.5 authorized for use in individuals 6 months of age, supplied as a 0.10 mg/mL suspension in a 2.5 mL multidose vial with a royal blue cap and coral blue label border.

No dilution is required.

The volume required differs by age: 0.25 mL (25 mcg) for 6 months to 11 years and 0.5 mL (50 mcg) for 12 years of age and over.

Novavax Nuvaxovid Original COVID-19 vaccine

Each dose is 0.5 mL, containing 5 mcg SARS-CoV-2 recombinant original strain spike protein. Vials contain 5 mcg/0.5 mL in a 5.0 mL multidose vial.

The product comes premixed with the Matrix-M adjuvant. No dilution or reconstitution is required.

Novavax Nuvaxovid XBB.1.5 COVID-19 vaccine

Note that XBB.1.5 vaccines are now recommended. Recommendations regarding the use of the protein subunit vaccine are currently under review by NACI.

Each dose is 0.5 mL, containing 5 mcg SARS-CoV-2 recombinant XBB.1.5 strain spike protein. Vials contain 5 mcg/0.5 mL in a 5.0 mL multidose vial.

The product comes premixed with the Matrix-M adjuvant. No dilution or reconstitution is required.

Table 4. Overview of authorized mRNA XBB.1.5 vaccines by product and age
Age group Dose Description Dilution required
Pfizer- BioNTech Comirnaty XBB.1.5
6 months to 4 years 3 mcg (0.2 mL) Cap and label colour: Maroon Yes (with 2.2 mL of 0.9% Sodium Chloride)
5 years to 11 years 10 mcg (0.3 mL) Cap and label colour: Blue No
12 years of age and over 30 mcg (0.3 mL) Cap and label colour: Grey No
Moderna Spikevax XBB.1.5
6 months to 11 years 25 mcg (0.25 mL) 0.10 mg/mL
Cap colour: Royal blue;
Label colour: Coral blue
No
12 years of age and over 50 mcg (0.5 mL)

Route of administration

COVID-19 vaccines are given as an intramuscular (IM) injection. The deltoid muscle of the arm is the preferred injection site in adolescents and adults, unless the muscle mass is not adequate or vaccination in that site is not possible, in which case the anterolateral thigh can be used.

Refer to Vaccine administration practices in Part 1 for additional general information, including recommended routes of administration for children.

If an error in vaccine administration occurs, refer to Managing COVID-19 vaccine administration errors or deviations for guidance.

Interchangeability of vaccines

When an XBB.1.5 vaccine is used to complete the series started with another COVID-19 vaccine formulation (either original monovalent wild type-containing or bivalent vaccine), the previous dose should be counted and the series need not be restarted. See Table 2 for information on completing the vaccination series when previous vaccines were non-XBB.1.5 products.

MRNA vaccines are the preferred product. Novavax Nuvaxovid XBB.1.5 should be used to start or complete a primary series, or used as a booster dose in a mixed prime-boost series, for individuals who are not able or willing to receive an mRNA vaccine. Recommendations regarding the use of the protein subunit vaccine are currently under review by NACI.

Informed consent should include a discussion of the benefits and risks given the limited data available on mixed schedules with the protein subunit vaccine. Clinical trial evidence for a heterologous booster dose with Novavax Nuvaxovid original is available from two randomized controlled trials where adults received a booster dose at least 12 weeks after a primary series with mRNA COVID-19 vaccines or viral vector COVID-19 vaccines. In one, humoral and cellular immune responses against original SARS-CoV-2 were lower compared to after Pfizer-BioNTech Comirnaty original or Moderna Spikevax original. In the other, humoral immune responses were similar to or slightly higher. In both trials, Novavax Nuvaxovid original was less reactogenic compared to mRNA COVID-19 vaccines. Evidence on immune responses against recent Omicron sub-lineages is also available from an observational study that showed that a heterologous booster dose of Novavax Nuvaxovid original resulted in neutralizing antibody responses against BQ.1.1 and XBB.1 that were slightly lower (but not statistically significant) compared to responses after a bivalent mRNA booster dose.

Mixed COVID-19 vaccine schedules for the primary series

For mixed COVID-19 vaccine primary series (i.e., primary series using vaccines products from more than one manufacturer) schedules, the minimum interval between doses should be based on the minimum interval of the product used for the first dose. When using mixed schedules, the recommended interval between doses is 8 weeks for those who are not moderately to severely immunocompromised and 4 to 8 weeks for those who are moderately to severely immunocompromised. Evidence indicates that mixed COVID-19 mRNA and protein subunit vaccine schedules with dosing intervals between 4 and 12 weeks have acceptable safety profiles, although this evidence is not available for the XBB.1.5 vaccines.

Limited evidence suggests that a mixed schedule in which Novavax Nuvaxovid original is administered following a partial or complete primary series of AstraZeneca Vaxzevria or Pfizer-BioNTech Comirnaty original COVID-19 vaccines may not be as immunogenic as continuing with Pfizer-BioNTech Comirnaty original or Moderna Spikevax original vaccines, noting that Novavax Nuvaxovid original had an acceptable safety profile and immunogenicity. No data is available for mixed schedules using Novavax Nuvaxovid XBB.1.5 for the primary series.

Concurrent administration with other vaccines

For individuals 6 months of age and older, COVID-19 vaccines may be given concurrently (i.e., same day), or at any time before or after non-COVID-19 vaccines (including live and non-live vaccines).

Concurrent administration will reduce barriers to the provision of routine childhood immunizations and seasonal influenza immunization. Studies and surveillance activities to assess the safety and immunogenicity of concurrent administration of COVID-19 vaccines with other vaccines have been re-assuring to date and are ongoing.

If more than one type of vaccine is administered at a single visit, they should be administered at different injection sites using separate injection equipment. Preferably this is in different limbs, however if the same limb must be used, the injection sites should be separated by at least 2.5 cm (1 inch). COVID-19 vaccines should never be mixed in the same syringe as other vaccines.

Informed consent should include a discussion of the benefits and risks given the limited data available on administration of COVID-19 vaccines at the same time as, or shortly before or after, other vaccines.

Refer to Timing of vaccine administration in Part 1 for additional general information on concurrent administration of other vaccines.

Pre-vaccination counselling

Prior to providing a COVID-19 vaccine, informed consent should include discussion about frequently occurring minor adverse events and the risks and symptoms of potential rare severe adverse events.

Anyone receiving any mRNA COVID-19 vaccine should be informed of the risks associated with mRNA COVID-19 vaccines: myocarditis/pericarditis, Bell's palsy and anaphylaxis, and be advised to seek medical attention if they develop signs or symptoms suggestive of these conditions.

Anyone receiving the protein subunit vaccine should be informed of the risk of myocarditis/pericarditis and anaphylaxis and also be advised to seek medical attention if they develop signs or symptoms suggestive of these conditions.

Prophylactic oral analgesics or antipyretics (e.g., acetaminophen or ibuprofen) should not be routinely used before or at the time of vaccination, but their use is not a contraindication to vaccination. There is currently no evidence of benefit from administration of oral analgesics for the prevention of immunization injection pain or systemic reactions.

Refer to Safety and adverse events for further information.

Post-vaccination counselling

Vaccine recipients should be kept under observation for at least 15 minutes after immunization; 30 minutes is a preferred interval when there is a specific concern about a possible vaccine reaction (see Other allergies for additional information).

All vaccine recipients should be instructed to seek medical care if they develop signs or symptoms of a serious adverse event or an allergic reaction following vaccination.

Oral analgesics or antipyretics may be considered for the management of adverse events (e.g., pain or fever, respectively), if they occur after vaccination. Analgesics and antipyretics were used in clinical trials of COVID-19 vaccines for the management of pain and/or fever after vaccination.

Refer to Vaccine administration practices in Part 1 for additional information on pre- and post-vaccination counseling.

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Storage requirements

For information on storage, handling and transport of frozen and thawed vaccine vials, refer to the Overview of key features of COVID-19 vaccines authorized in Canada.

For additional information, consult the product leaflet or information contained within the product monograph available through Health Canada's Drug Product Database. Refer to Storage and handling of immunizing agents in Part 1 for additional general information.

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Safety and adverse events

Evidence on vaccine safety is available from COVID-19 clinical trials and ongoing national and international COVID-19 vaccine safety monitoring. The clinical trials solicited adverse events for defined lengths of time following a vaccine dose, as well as collecting unsolicited and serious events.

For reported side effects following COVID-19 vaccination in Canada, refer to the PHAC AEFI report.

Refer to Vaccine safety and pharmacovigilance and Adverse events following immunization (AEFI) in Part 2 for additional information on vaccine safety and for definitions of AEFIs, and reporting of AEFI to public health.

For individuals who develop AEFIs following COVID-19 vaccination, refer to the Contraindications and precautions section for advice on future vaccinations.

Very common and common adverse events

Common adverse events are defined as those that occur in 1% to less than 10% of vaccine recipients; very common adverse events occur in 10% or more of vaccine recipients.

Local

Local adverse events were usually mild or moderate and resolved within a few days of vaccination in all age groups (6 months and older). Pain at the injection site was very common. Redness and swelling were common or very common after administration of any authorized COVID-19 vaccine. Localized axillary (or groin) swelling and tenderness (lymphadenopathy) was a solicited adverse event in the Moderna Spikevax original COVID-19 vaccine clinical trial and was very common after administration of that vaccine.

Systemic

Systemic adverse events were usually mild or moderate and resolved within a few days of vaccination in all age groups (6 months and older). Fatigue, headache, muscle pain, chills, and joint pain were all either common or very common after the administration of any authorized COVID-19 vaccine.

The most frequent reactions reported for children aged 6 months to 2 years included irritability or crying, sleepiness, and loss of appetite. These reactions are common after childhood vaccination.

Adverse events in individuals previously infected with SARS-CoV-2

Limited evidence suggests reactogenicity may be slightly increased in individuals previously infected with SARS-CoV-2 compared to those with no history of previous infection; however, this evidence is limited to the primary series and infection with variants prior to Omicron.

Adverse events following updated mRNA COVID-19 vaccines

Available clinical trial data show that Moderna Spikevax Bivalent BA.1 (50 mcg) and Pfizer-BioNTech Comirnaty Bivalent BA.4/5 (30 mcg) administered as a second booster (second additional) dose to individuals 18 years of age and older and 12 years of age and older, respectively, had similar reactogenicity profiles to that of the respective original versions of each vaccine given as a second booster dose in adults. In a clinical trial, Moderna Spikevax XBB.1.5 (50 mcg) administered as a third booster dose to individuals 18 years of age and older had a similar reactogenicity profile to that of Moderna Spikevax Bivalent BA.4/5 (50 mcg) given as a second booster dose and Moderna Spikevax original (50 mcg) given as a first booster dose in adults.

For Omicron BA.4/5 mRNA bivalent vaccines, post-market safety surveillance data in individuals 12 years of age and older from Canada and the US suggest they are well tolerated with a similar safety profile to the original mRNA COVID-19 vaccines when administered as booster doses.

Uncommon, rare and very rare adverse events

Uncommon adverse events occur in 0.1% to less than 1% of vaccine recipients. Rare and very rare adverse events occur in 0.01% to less than 0.1% and less than 0.01% of vaccine recipients, respectively. The probability of detection of very rare adverse events in clinical trials is low given clinical trial sample sizes; therefore, ongoing pharmacovigilance is essential.

Lymphadenopathy

Lymphadenopathy was an unsolicited event that was uncommonly reported after administration of the Pfizer-BioNTech Comirnaty original (both 10 mcg and 30 mcg formulations) in clinical trials. As noted above, lymphadenopathy was a solicited adverse event in the clinical trials for Moderna Spikevax original and was very commonly reported.

Myocarditis and/or pericarditis following vaccination with mRNA and other COVID-19 vaccines

Rare cases of myocarditis (inflammation of the heart muscle) and/or pericarditis (inflammation of the lining around the heart) have been reported following vaccination with COVID-19 mRNA vaccines.

Cases following mRNA COVID-19 vaccination are consistently reported to have occurred:

Analyses of primary series surveillance data in Canada, US and European Nordic countries suggests a higher rate of myocarditis/pericarditis cases reported after vaccination with Moderna Spikevax original (100 mcg) compared to Pfizer-BioNTech Comirnaty original (30 mcg) vaccine especially among 12 to 29 year old males following a second dose of vaccine. Longer intervals between doses have been noted to result in lower rates of myocarditis/pericarditis; however the rates specific to the XBB.1.5 mRNA vaccines are currently unknown.

Myocarditis unrelated to exposure to COVID-19 disease or COVID-19 vaccines is typically less common in younger children 5 to 11 years of age. Among children 5 to 11 years of age following vaccination with Pfizer-BioNTech Comirnaty original (10 mcg), very rare cases were most often reported following dose 2 and among males. The risk of myocarditis or pericarditis with Moderna Spikevax original (50 mcg) in children 6 to 11 years of age is unknown. Post-market safety surveillance is ongoing.

Available post-market vaccine safety data from V-safe, Vaccine Safety Datalink (VSD) and Vaccine Adverse Event Reporting System (VAERS) in the US as of September 2022 show that the Moderna Spikevax (25 mcg) and Pfizer-BioNTech Comirnaty (3 mcg) mRNA COVID-19 vaccines are well tolerated among children aged 6 months to 5 years. No safety signals (including myocarditis) have been identified after administration of about 1.5 million vaccine doses.

Evidence from bivalent and original mRNA COVID-19 vaccines across different age groups show that the risk of myocarditis is lower following boosters compared to dose 2 of the primary series, and that no product-specific difference in the risk of myocarditis has been identified following a booster dose at this time, including in adolescents 12 to 17 years of age. However, the use of Moderna Spikevax COVID-19 vaccines have been limited in those 5 to 17 years of age. While long-term follow-up is ongoing, available data indicate that the majority of individuals who reported myocarditis/pericarditis after mRNA COVID-19 vaccination, though requiring hospitalization, have responded well to conservative therapy and tend to recover quickly.

Healthcare providers should consider myocarditis/pericarditis in their evaluation if the patient presents with clinically compatible symptoms (e.g., chest pain, shortness of breath, palpitations) after an mRNA COVID-19 vaccine regardless of timing from vaccination to symptoms onset. Investigations include electrocardiogram, serum troponins and echocardiogram. Abnormal electrocardiogram findings and elevated troponin levels have been frequently noted with myocarditis/pericarditis following mRNA vaccine.

Consultation with a cardiologist, infectious disease specialist, or internal medicine specialist may be advisable to assist in this evaluation, particularly to investigate the many potential causes of myocarditis and pericarditis. Investigations may include diagnostic testing for acute COVID-19 infection (e.g., PCR testing), prior SARS-CoV-2 infection and consideration of other potential infectious or non-infectious etiologies including auto-immune conditions.

Cases of myocarditis/pericarditis have been rarely reported following the administration of Novavax Nuvaxovid original. Australia's Therapeutic Goods Administration (TGA) reports that as of April 16, 2023, over 251,000 doses of Novavax Nuvaxovid original had been administered in the country. Myocarditis was reported in approximately 3 to 4 in every 100,000 people who received a dose of this vaccine. Pericarditis was reported in 13 in every 100,000 people.

A further breakdown of the rates of myocarditis/pericarditis after Novavax Nuvaxovid original by age group (including among adolescents), sex and dose number are not available due to the relatively low number of doses given and reported cases. In Europe, over 345,000 doses of Novavax Nuvaxovid original have been administered as of December 31, 2022 and myocarditis has been reported at a rate of 20.3 per million doses. In Japan, over 275,000 doses of Novavax Nuvaxovid original have been administered as of December 31, 2022, with no reported cases of myocarditis. In Canada, there have been no reported cases of myocarditis or pericarditis following Novavax Nuvaxovid original as of March 26, 2023 (following approximately 32,200 doses administered).

Refer to the Contraindications and precautions section for advice on re-vaccination of individuals who developed myocarditis/pericarditis after a COVID-19 vaccine.

Bell's palsy

Very rare cases of Bell's palsy (typically temporary weakness or paralysis on one side of the face) have been reported following vaccination with mRNA COVID-19 vaccines (Pfizer-BioNTech Comirnaty original or Moderna Spikevax original) among individuals aged 12 years and older. Symptoms of Bell's palsy appear suddenly and generally start to improve after a few weeks. The exact cause is unknown. It's believed to be the result of swelling and inflammation of the nerve that controls muscles on the face.

Symptoms of Bell's palsy may include:

Individuals should seek medical attention if they develop symptoms of Bell's palsy following receipt of COVID-19 vaccines. Healthcare providers should consider Bell's palsy in their evaluation if the patient presents with clinically compatible symptoms after a COVID-19 vaccine. Investigations should exclude other potential causes of facial paralysis.

Multisystem inflammatory syndrome in children or in adults (MIS-C or MIS-A) following vaccination with an mRNA COVID-19 vaccine

During the manufacturer-led clinical trials for mRNA COVID-19 vaccines, no cases of MIS-C were reported among children or adolescents. However, any rare or very rare AE that occurs at a frequency less often than 1 in 10,000 would likely not be detected due to the limitations of the trial size.

Very rare cases of MIS-C or MIS-A have been reported following vaccination with COVID-19 mRNA vaccines in Canada and internationally among individuals aged 12 years and older. In October 2021, the European Medicines Agency (EMA) Pharmacovigilance Risk Assessment Committee (EMA-PRAC) issued a statement that there is currently insufficient evidence regarding a possible link between mRNA COVID-19 vaccines and very rare cases of MIS-C or MIS-A.

Severe immediate allergic reactions (e.g., anaphylaxis) following vaccination with COVID-19 vaccines

Anaphylaxis is a very rare, severe, life-threatening allergic reaction typically with a rapid onset that involves multiple organ systems and can progress rapidly. Symptoms and signs of anaphylaxis may include but are not limited to generalized urticaria; wheezing; swelling of the mouth, tongue, and throat; difficulty breathing; vomiting; diarrhea; hypotension; decreased level of consciousness; and shock.

Very rare cases of severe immediate allergic reactions (e.g., anaphylaxis) have been reported following vaccination with mRNA COVID-19 vaccines. Most of the reported cases have occurred within 30 minutes of vaccination.

Individuals tend to recover quickly with appropriate treatment and there have been no fatalities nor long-term morbidity observed with any of these severe immediate allergic reactions in Canada.

Studies have shown that individuals with a severe immediate allergic reaction after a previous dose of mRNA vaccine can be re-vaccinated with the same vaccine or another mRNA COVID-19 vaccine following an appropriate medical assessment. In these studies, re-vaccination was safe and well tolerated with predominantly no, or mild, reactions after re-vaccination when provided in a controlled environment. Available evidence also suggests that most of the reported severe immediate allergic reactions following mRNA COVID-19 vaccines are likely not immunoglobulin E (IgE)-mediated and therefore have a low risk of recurrence following future vaccine doses. Refer to Precautions below for additional information.

Refer to Anaphylaxis and other acute reactions following vaccination in Part 2 for information on the management of anaphylaxis post-vaccination.

Refer to the Contraindications and precautions section for advice on re-vaccination of individuals who had an anaphylactic reaction after vaccination and for vaccination advice for those allergic to components of the COVID-19 vaccines.

Adverse events following vaccination with viral vector vaccines

A number of serious adverse events were observed after the previously available viral vector vaccines Vaxzevria, COVISHIELD and Jcovden (see Preparations authorized for use in Canada).

Venous thromboembolism (VTE) has been observed rarely following vaccination with the Janssen Jcovden COVID-19 Vaccine.

Guillain-Barré syndrome (GBS), a rare but potentially serious immune-mediated neurologic disorder, was identified as having an increased risk following vaccination with the viral vector COVID-19 vaccines (AstraZeneca Vaxzevria and Janssen Jcovden).

Cases of immune thrombocytopenia (ITP) with very low platelet levels (<20,000 per µL) have been reported very rarely after vaccination with Janssen Jcovden and AstraZeneca Vaxzevria COVID-19 vaccines, usually within the first four weeks after vaccination.

Very rare cases of capillary leak syndrome (CLS) have been reported following immunization with the viral vector COVID-19 vaccines (AstraZeneca Vaxzevria and Janssen Jcovden). CLS is a very rare, serious condition that causes fluid leakage from capillaries.

Very rare cases of serious blood clots or thrombosis (at unusual sites such as cerebral venous sinus thrombosis, splanchnic vein thrombosis, as well as arterial thrombosis) associated with thrombocytopenia have been reported following vaccination with viral vector COVID-19 vaccines. These were known as thrombosis with thrombocytopenia syndrome (TTS) along with cases that tested positive for a biomarker, anti-PF4 (antibodies to platelet factor 4-polyanion complexes), representing a subset of events referred to as vaccine-induced immune thrombotic thrombocytopenia (VITT). The exact mechanism by which the viral vector COVID-19 vaccines trigger this syndrome is still under investigation.

Guidance on reporting adverse events following immunization (AEFI)

Vaccine providers are asked to report AEFIs through local public health departments and to follow AEFI reporting requirements that are specific to their province or territory. In general, any serious (defined as resulting in hospitalization, permanent disability or death) or unexpected adverse event that is temporally related to vaccination should be reported. Refer to Reporting AEFI in Canada for additional information on the completion and submission of AEFI reports.

At the international level, the Brighton Collaboration has developed a list of Adverse Events of Special Interest (AESI). AESI are pre-specified medically significant events that have the potential to be causally associated with a vaccine product. Refer to Brighton Collaboration: COVID-19 resources and tools for the list of AESIs and for case definitions of specific AEFIs.

Refer to Adverse events following immunization (AEFI) in Part 2 for additional information on definitions, reporting, investigating and managing, and causality assessments for AEFIs.

Refer to the PHAC weekly report for reported adverse events following COVID-19 vaccination in Canada.

Contraindications and precautions

Contraindications

In general, vaccines are contraindicated in individuals who are hypersensitive to the active ingredient or to any ingredient in the formulation, including any non-medicinal ingredient, or component of the container. For COVID-19 vaccines, in some cases, individuals with a known or suspected hypersensitivity may receive the vaccine under medical supervision. See Precautions for more details.

See the Contraindications and precautions chapter for more information on allergies.

Precautions

Hypersensitivity and allergies

Severe immediate allergic reaction (e.g., anaphylaxis) to an mRNA COVID-19 vaccine

In individuals with a history of a severe, immediate (4 hours or less following vaccination) allergic reaction after previous administration of an mRNA COVID-19 vaccine, re-vaccination may be offered with the same vaccine or the same platform if a risk assessment deems that the benefits outweigh the potential risks for the individual and if informed consent is provided. Consultation with an allergist or other appropriate physician should be sought prior to re-vaccination. If re-vaccinated, vaccine administration should be done in a controlled setting with expertise and equipment to manage anaphylaxis. Individuals should be observed for at least 30 minutes after re-vaccination. For example, a longer period of observation is warranted for individuals exhibiting any symptom suggestive of an evolving AEFI at the end of the 30-minute observation period.

For those with a previous history of allergy to an mRNA vaccine where consultation with an allergist or other appropriate physician precludes further vaccination with an mRNA vaccine, vaccination with Novavax Nuvaxovid XBB.1.5 should be offered if the individual is in the authorized age group and does not have contraindications to the vaccine. They should also be observed for an extended period of at least 30 minutes after re-vaccination.

Confirmed allergies to a component of a COVID-19 vaccine

Ingredients of authorized COVID-19 vaccines that have been associated with allergic reactions in other products are: polyethylene glycol (PEG), tromethamine (trometamol or Tris) and polysorbate 80. There is a potential of cross-reactive hypersensitivity between PEG and polysorbate.

All mRNA vaccines (Pfizer Bio-NTech and Moderna Spikevax) have polyethylene glycol (PEG) and tromethamine (trometamol or Tris) but no polysorbate 80.

Novavax Nuvaxovid (both the original and XBB.1.5 vaccines) has polysorbate 80 but no polyethylene glycol (PEG) or tromethamine (trometamol or Tris).

In individuals with a confirmed severe, immediate (≤4 hours following exposure) allergy (e.g., anaphylaxis) to a component of a specific COVID-19 vaccine (e.g., PEG), or its container, consultation with an allergist is recommended before receiving the specific COVID-19 vaccine. In individuals with a serious PEG allergy in whom mRNA vaccination is precluded based on a consultation with an allergist or other appropriate physician, vaccination with Novavax Nuvaxovid XBB.1.5 may be preferred for individuals in the authorized age group without contraindications to Novavax Nuvaxovid XBB.1.5. Individuals with a known or suspected serious allergy to a component of a COVID-19 vaccine should be observed for at least 30 minutes after vaccination, if they receive a vaccine containing that component.

It is important to note that other, less serious reactions may mimic allergic reactions (e.g., vasovagal syncope) and vaccination is not contraindicated in these cases.

Mild to moderate immediate allergic reactions to a COVID-19 vaccine or a vaccine excipient

In individuals with mild to moderate immediate allergic reactions (defined as limited in the scope of symptoms and involvement of organ systems or even localized to the site of administration) to a previous dose of mRNA COVID-19 vaccine or any of its components, re-vaccination may be offered with the same vaccine or the same platform (i.e., mRNA). Assessment by a physician or nurse with expertise in immunization may be warranted prior to re-immunization. They should also be observed for an extended period of at least 30 minutes after re-vaccination.

Other allergies

The following individuals may be routinely vaccinated with COVID-19 vaccines with the following recommended observation periods.

30 minute post-vaccination observation period:

15 minute post-vaccination observation period:

Acute illness

Vaccination of individuals who may be currently infected with SARS-CoV-2 is not known to have a detrimental effect on the illness. However, vaccination should be deferred in individuals with confirmed or suspected SARS-CoV-2 infection, or those with respiratory symptoms, to minimize the risk of COVID-19 transmission at an immunization clinic/venue. If any person is identified with symptoms on arrival at the venue, they should not be immunized and should be instructed to seek medical and public health advice as appropriate and follow current local public health measures.

See Individuals previously infected with SARS-CoV-2 section for additional information.

Bleeding disorders

In individuals with bleeding disorders, the condition should be managed prior to immunization to minimize the risk of bleeding. Individuals receiving long-term anticoagulation are not considered to be at higher risk of bleeding complications following immunization and may be safely immunized without discontinuation of their anticoagulation therapy.

Refer to Immunization of persons with chronic diseases for more information on the immunization of persons with bleeding disorders.

Myocarditis and/or pericarditis following vaccination

As a precautionary measure until more information is available, further doses of mRNA COVID-19 vaccines should be deferred among individuals who have experienced myocarditis and/or pericarditis within 6 weeks following a previous dose of an mRNA COVID-19 vaccine in most circumstances. This includes any person who had an abnormal cardiac investigation including ECG, elevated troponins, echocardiogram or cardiac MRI after a dose of an mRNA COVID-19 vaccine.

Those with a history compatible with pericarditis and who either had no cardiac workup or had normal cardiac investigations, can receive the next dose once they are symptom-free and at least 90 days have elapsed since vaccination.

Some individuals with confirmed myocarditis and/or pericarditis after a dose of an mRNA COVID-19 vaccine may choose to receive another dose of vaccine after discussing the risk and benefit with their healthcare provider. If another dose of vaccine is offered, it should be with a Pfizer-BioNTech Comirnaty COVID-19 XBB.1.5 vaccine product due to the lower reported rate of myocarditis and/or pericarditis following the Pfizer-BioNTech Comirnaty original (30 mcg) vaccine compared to the Moderna Spikevax original (100 mcg) vaccine among individuals 12 years of age and older. Informed consent should include discussion about the unknown risk of recurrence of myocarditis and/or pericarditis following receipt of additional doses of Pfizer-BioNTech Comirnaty vaccines in individuals with a history of confirmed myocarditis and/or pericarditis after a previous dose of mRNA COVID-19 vaccine, as well as the need to seek immediate medical assessment and care should symptoms develop.

There have been case reports of myocarditis and/or pericarditis following the administration of Novavax Nuvaxovid original. Data from the clinical trials and global safety surveillance have suggested an increased risk.

Individuals who have a history of myocarditis unrelated to mRNA or protein subunit COVID-19 vaccination should consult their clinical team for individual considerations and recommendations. If the diagnosis is remote and they are no longer followed clinically for cardiac issues, they should receive the vaccine.

Guillain-Barré syndrome

Individuals with past history of GBS unrelated to COVID-19 vaccination should receive an mRNA COVID-19 XBB.1.5 vaccine. When mRNA COVID-19 vaccines are contraindicated, Novavax Nuvaxovid XBB.1.5 should be considered.

Individuals who developed GBS after a previous dose of a COVID-19 vaccine may receive an mRNA COVID-19 vaccine, after consultation with their health care provider if it is determined that the benefits outweigh the risk and informed consent is provided.

Bell's palsy

Individuals should seek medical attention if they develop symptoms compatible with Bell's palsy following receipt of mRNA COVID-19 vaccines. Healthcare providers should consider Bell's palsy in their evaluation if the patient presents with clinically compatible symptoms after an mRNA COVID-19 vaccine. Investigations should exclude other potential causes of facial paralysis.

Multisystem inflammatory syndrome in children or adults (MIS-C or MIS-A)

For children or adults with a previous history of MIS-C or MIS-A, vaccination or re-vaccination should be postponed until clinical recovery has been achieved or until it has been 90 days or more since diagnosis, whichever is longer.

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Other considerations

Tuberculin skin testing (TST) or interferon gamma release assay (IGRA)

There is a theoretical risk that mRNA vaccines could temporarily affect cell-mediated immunity, resulting in false-negative TST or IGRA test results. However, there is no direct evidence for this interaction. Therefore, in the absence of data and acknowledging the importance of both timely tuberculosis testing and immunization, vaccination with COVID-19 vaccines may take place at any time before, after or at the same visit as the TST or IGRA test. Repeat tuberculin skin testing or IGRA (at least 4 weeks post-COVID-19 immunization) of individuals with negative TST or IGRA results for whom there is high suspicion of latent tuberculosis infection may be considered in order to avoid missing persons with TB infection.

Blood products, human immunoglobulin and timing of immunization

It is recommended that COVID-19 vaccines should not be given concurrently with anti-SARS-CoV-2 monoclonal antibodies.

Administration of these products concurrently may result in decreased effectiveness of the COVID-19 vaccine and/or anti-SARS-CoV-2 monoclonal antibodies. Anti-SARS-CoV-2 monoclonal antibodies have high affinity for the spike protein expressed by COVID-19 vaccines, which could prevent the production of antibodies stimulated by the vaccine, or binding of vaccine antigen to the monoclonal antibody may neutralize the monoclonal antibody.

Pre-exposure prophylaxis for COVID-19 with anti-SARS-CoV-2 monoclonal antibodies

Up-to-date information on alerts including risk of treatment failure of specific anti-SARS-CoV-2 monoclonal antibodies as well as safety and recalls, is available from Health Canada.

Guidance on anti-SARS-CoV-2 monoclonal antibodies may change as additional evidence emerges.

Administration of COVID-19 vaccines following anti-SARS-CoV-2 monoclonal antibodies

There is no evidence on which to base a specific minimum interval for COVID-19 vaccination following anti-SARS-CoV-2 monoclonal antibodies administration. Timing should be assessed in consultation with clinical experts on a case-by-case basis.

Therapeutic management of COVID-19 with anti-SARS-CoV-2 monoclonal antibodies

Multiple products are authorized in Canada for therapeutic management of COVID-19. Expert clinical opinion should be sought on a case-by-case basis when deciding on the use of anti-SARS-CoV-2 monoclonal antibodies, as well as whether vaccination should be repeated if a therapeutic dose is given too close to vaccination.

Timing of administration of COVID-19 vaccines following administration of therapeutic anti-SARS-CoV-2 monoclonal antibodies should be assessed in consultation with clinical experts on a case-by-case basis.

For complete prescribing information, consult the product leaflet or information contained within the product monograph available through Health Canada's Drug Product Database.

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Chapter revision process

This chapter was updated to further reflect the authorization of Novavax Nuvaxovid XBB.1.5 vaccine since the last version of this chapter (December 5, 2023).

For supporting information on COVID-19 vaccine chapter updates, including additional references, refer to the current and/or previous summary of updates in the Canadian Immunization Guide published on the NACI webpage under COVID-19.

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Acknowledgements

This chapter was prepared by B Warshawsky, C Jensen, R Krishnan, R Pless, E Wong, J Zafack, MI Salvadori, N Forbes, E Abrams, K Young, MC Tunis, S Wilson, R Harrison, and S Deeks on behalf of NACI.

NACI gratefully acknowledges the contribution of: N Haddad.

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