Question Period Note: NACI RECOMMENDATIONS ON THE USE OF COVID-19 VACCINES

NACI may make recommendations that are broader or narrower than the conditions of use approved by Health Canada (known as ‘off-label’ recommendations). As regulator, Health Canada rigorously evaluates safety and efficacy data from clinical trials before authorizing vaccines, but does not dictate practice of medicine or make recommendations on how the vaccines should be used for public health impact.

• Canada’s National Advisory Committee on Immunization (NACI) updates its recommendations on COVID-19 vaccines based on the latest scientific evidence and its expert opinions.
• COVID-19 vaccines authorized for use in Canada have been essential in saving lives and protecting the health of Canadians.
• In addition to high vaccination coverage, public health measures, like wearing a well-fitting mask, hand hygiene and physical distancing, continue to be essential to reduce and control transmission of the virus, especially variants.

If pressed on guidance on second booster doses
• NACI recommends that provinces and territories prepare to offer a second booster dose at least 6 months after the receipt of a first booster dose to certain populations in the coming weeks, due to concerning COVID-19 trends.
• NACI strongly recommends the prioritization of adults 80 years of age and over living in the community and residents of long-term care homes or other congregate living settings for seniors.
• Jurisdictions may consider offering a second COVID-19 booster dose to adults 70-79 years of age living in the community.
• Second booster doses may also be considered for adults younger than 70 years of age who are living in or are from First Nations, Métis, or Inuit communities. These decisions should be made by Indigenous Peoples with the support of healthcare and public health partners.
• While not recommended at this time, second booster doses may be needed for other high-risk groups and the general population in the future.

If pressed on the use of mRNA COVID-19 vaccines in children 5 to 11 years of age
• NACI strongly recommends that a complete series of an mRNA COVID-19 vaccine should be offered to children in the authorized age groups who do not have contraindications to the vaccine, with a dosing interval of at least 8 weeks between the first and second dose.
• The Pfizer-BioNTech Comirnaty COVID-19 vaccine is preferred to start or continue the primary vaccine series in this age group due to its well-known safety profile.
• It is essential that children and their caregivers are supported and respected during the decision-making process so they are able to make an informed decision about COVID-19 vaccination.

If pressed on myocarditis and pericarditis in adolescents and young adults
• Rare cases of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the heart lining) following vaccination with mRNA COVID-19 vaccines have been reported in Canada and internationally.
• Most cases have occurred in males 12 to 29 years of age and after the second dose of an mRNA COVID-19 vaccine. Most cases have been mild and resolved quickly.
• US data suggests that the risk of myocarditis and/or pericarditis following vaccination with the Pfizer-BioNTech Comirnaty COVID-19 vaccine may be much lower in children 5 to 11 years of age compared to adolescents and young adults.
• The benefits of receiving an mRNA COVID-19 vaccine continue to outweigh any potential risks, including the rare risk of experiencing myocarditis and/or pericarditis after vaccination. COVID-19 can cause severe illness, hospitalization and death, as well as severe health complications, including myocarditis and pericarditis, due to infection.
• NACI continues to strongly recommend that individuals 5 years of age and older receive a complete series of an mRNA COVID-19 vaccine.
• The Pfizer-BioNTech Comirnaty COVID-19 vaccine is preferred in adolescents and young adults 12 to 29 years of age to further reduce the already rare risk of myocarditis/pericarditis following mRNA COVID-19 vaccination.
• The Pfizer-BioNTech Comirnaty COVID-19 vaccine is also preferred in children due to its well-known safety profile and our experience with the two mRNA COVID-19 vaccines in adolescents.

If pressed on guidance on first booster doses
• In addition to their strong recommendations for first booster doses in those 50 years of age and over, NACI now strongly recommends that the following people receive a first booster dose at least six months after the last dose of their primary series:
- all adults 18 to 49 years of age and older; and
- high-risk adolescents 12 to 17 years of age, including those who:
 have an underlying medical condition that puts them at high risk of severe outcomes from COVID-19, including adolescents who are moderately to severely immunocompromised and have already received a 3-dose primary series (this would be a fourth dose for those who are moderately to severely immunocompromised and had already received 3 doses);
 are residents of congregate living settings; and
 belong to racialized and/or marginalized communities disproportionately affected by COVID-19.
• NACI has also added a new discretionary recommendation that all other adolescents 12 to 17 years of age may be offered a first booster at least six months after the last dose of their primary series.
• NACI’s recommendations on the use of booster doses among adolescents aged 12 to 17 years are off-label recommendations as regulatory review for COVID-19 booster doses among adolescents is ongoing at Health Canada.
• The Pfizer-BioNTech Comirnaty COVID-19 vaccine is preferred as a booster for adolescents and young adults 12 to 29 years of age to further reduce the rare risk of myocarditis/pericarditis.

To date, NACI has published recommendations on the use of the Pfizer-BioNTech Comirnaty (10 mcg and 30 mcg), Moderna Spikevax (50 mcg and 100 mcg), AstraZeneca Vaxzevria, Johnson & Johnson, Novavax Nuvaxovid, and Medicago Covifenz COVID-19 vaccines, as well as guidance on subjects such as extended dose intervals, the interchangeability of vaccines, co-administration of COVID-19 vaccines with other vaccines, additional doses for immunocompromised individuals, guidance on COVID-19 vaccines for individuals with a history of COVID-19, and the use of booster doses. NACI continues to closely monitor the evolving evidence on COVID-19 and COVID-19 vaccines and updates its recommendations as needed.

Primary series for people 12 years of age and over

NACI preferentially recommends that a complete primary series with an mRNA COVID-19 vaccine (Pfizer-BioNTech Comirnaty [30 mcg] or Moderna Spikevax [100 mcg]) should be offered to individuals in the authorized age group (12 years of age and over) without contraindications to the vaccine, with a dosing interval of 8 weeks between first and second doses. This is due to the excellent protection they provide against severe illness and hospitalization and their well-known safety profiles.

Adults and adolescents who are moderately to severely immunocompromised should receive three doses of an authorized mRNA COVID-19 vaccine as their primary series with an interval of 4 to 8 weeks between each dose.

For individuals 12 to 29 years of age, the Pfizer-BioNTech Comirnaty COVID-19 vaccine (30 mcg) is preferred to start or continue the primary series due to a lower risk of myocarditis compared to the Moderna Spikevax COVID-19 vaccine (100 mcg).

NACI recommends a complete series of a recombinant protein subunit COVID-19 vaccine (Novavax Nuvaxovid) or a virus-like particle COVID-19 vaccine (Medicago Covifenz) may be offered to individuals in the authorized age group (18 years of age and over) without contraindications to the vaccine who are unable or unwilling to receive an mRNA COVID-19 vaccine.

NACI recommends that a complete series of a viral vector COVID-19 vaccine (AstraZeneca Vaxzevria, Janssen) may be offered to individuals in the authorized age group without contraindications to the vaccine only when all other authorized COVID-19 vaccines are contraindicated.

Primary series for children 5 to 11 years of age

There are two COVID-19 vaccines approved for use in children in Canada: the Pfizer-BioNTech Comirnaty mRNA COVID-19 vaccine (10 mcg) is authorized for children 5 to 11 years of age and the Moderna Spikevax mRNA COVID-19 vaccine (50 mcg) is authorized for children 6 to 11 years of age.

NACI strongly recommends that a complete series of an mRNA COVID-19 vaccine should be offered to children in the authorized age groups without contraindications to the vaccine, with a dosing interval of at least 8 weeks between first and second doses.

While NACI indicates that the Moderna Spikevax vaccine (50 mcg) may be offered to children 6 to 11 years of age, the Pfizer-BioNTech Comirnaty COVID-19 vaccine (10 mcg) is preferred over the Moderna Spikevax COVID-19 vaccine (50 mcg) to start or continue a primary vaccine series in children 5 to 11 years of age due to its well-known safety profile and the currently unknown risk of myocarditis/pericarditis following receipt of the Moderna Spikevax COVID-19 vaccine in this age group

Children 5 to 11 years of age who are moderately to severely immunocompromised should receive three doses of an mRNA COVID-19 vaccine as their primary series with an interval of 4 to 8 weeks between each dose. Administration of the Moderna Spikevax (50 mcg) vaccine as a 3-dose primary series may be considered for some immunocompromised individuals 6 to 11 years of age.

At this time, NACI recommends that children receive the pediatric Pfizer-BioNTech Comirnaty COVID-19 vaccine (10 mcg) at least 14 days before or after another vaccine. This is a precaution to help to determine if a side effect that may arise is due to the COVID-19 vaccine or another vaccine. There may be circumstances when a dose of a COVID-19 vaccine and another vaccine need to be given at the same time – a healthcare provider can help with this decision.

Health Canada, the Public Health Agency of Canada and NACI continue to monitor the safety and effectiveness of the mRNA COVID-19 vaccines in children 5 to 11 years of age and will provide updates if needed.

Intervals between COVID-19 vaccine doses

When authorizing a vaccine, Health Canada reviews clinical trial data submitted by the manufacturer. When developing its recommendations, NACI reviews clinical trial data and data from real-world use of the vaccine. NACI recommends an interval of at least 8 weeks between doses for the primary series due to emerging evidence in adults suggesting that, compared to shorter intervals, longer intervals between the first and second dose of a primary series result in a stronger immune response, higher vaccine effectiveness that is expected to last longer, and may be associated with a lower risk of myocarditis and/or pericarditis in adolescents and young adults.

Recommendations related to myocarditis and/or pericarditis

Rare cases of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the heart lining) following vaccination with mRNA COVID-19 vaccines have been reported in Canada and internationally. Most cases have occurred in males 12 to 29 years of age after a second dose of an mRNA COVID-19 vaccine. Most cases have been mild and resolved quickly. Based on US data, the risk of myocarditis/pericarditis may be much lower in children 5 to 11 years of age than adolescents 12 to 17 years of age.

In order to further minimize the rare risk of adolescents and young adults experiencing myocarditis and/or pericarditis, the Pfizer-BioNTech Comirnaty COVID-19 vaccine (30 mcg) is preferred for use in adolescents and young adults 12 to 29 years of age. Canadian and international data suggest the risk of myocarditis following vaccination with an mRNA COVID-19 vaccine is lower with the Pfizer-BioNTech Comirnaty COVID-19 vaccine (30 mcg) compared to the Moderna Spikevax COVID-19 vaccine (100 mcg), particularly after a second dose in males 12 to 29 years of age. The Pfizer-BioNTech Comirnaty COVID-19 vaccine is also preferred to start or continue the primary vaccines series in children, given the currently unknown risk of myocarditis and/or pericarditis for the Moderna Spikevax COVID-19 vaccine (50 mcg) in children 6 to 11 years of age, and the known higher risk of myocarditis/pericarditis for the Moderna Spikevax COVID-19 vaccine (100 mcg) compared to the Pfizer-BioNTech Comirnaty COVID-19 vaccine (30 mcg) among individuals 12 to 29 years of age when used for the primary series.

Based on clinical judgement, the Moderna Spikevax COVID-19 vaccine (100 mcg) may be considered for adolescents and adults 12 to 29 years of age who are moderately to severely immunocompromised given evidence that this vaccine may have a slightly higher vaccine effectiveness and may provide longer protection against infection and severe COVID-19 outcomes compared to the Pfizer-BioNTech Comirnaty COVID-19 vaccine (30 mcg).

Out of precaution, further doses of mRNA COVID-19 vaccines should be deferred among people who experienced myocarditis (with or without pericarditis) within 6 weeks of receiving a previous dose of an mRNA COVID-19 vaccine. Some people who experienced myocarditis with or without pericarditis after a first dose of an mRNA COVID-19 vaccine may choose to receive another dose of vaccine after discussing the risks and benefits with their healthcare provider. If another dose of vaccine is offered, they should be offered the Pfizer-BioNTech Comirnaty COVID-19 vaccine (30 mcg) due to the lower reported rate of myocarditis and/or pericarditis following this vaccine compared to the Moderna Spikevax COVID-19 vaccine (100 mcg).

Individuals who have a history of myocarditis unrelated to mRNA COVID-19 vaccination should consult their clinical team for individual considerations and recommendations. People previously diagnosed with myocarditis but who are no longer being followed by a medical professional for heart issues should receive the vaccine.

First Booster doses for people 12 years of age and over

A booster dose can enhance protection from a primary series that may have decreased over time. Both the Pfizer-BioNTech Comirnaty mRNA COVID-19 vaccine (30 mcg) and the Moderna Spikevax mRNA COVID-19 vaccine (50 mcg) are authorized for use as booster doses in Canada. The Moderna Spikevax COVID-19 vaccine booster dose is half (50 mcg) the dose of the Moderna Spikevax COVID-19 vaccine used for the primary series (100 mcg).

• In addition to their strong recommendations for first booster doses in those 50 years of age and over, NACI now strongly recommends that the following people receive a first booster dose at least six months after the last dose of their primary series:
- all adults 18 to 49 years of age and older; and
- high-risk adolescents 12 to 17 years of age, including those who:
 have an underlying medical condition that puts them at high risk of severe outcomes from COVID-19, including adolescents who are moderately to severely immunocompromised and have already received a 3-dose primary series (this would be a fourth dose for those who are moderately to severely immunocompromised and had already received 3 doses);
 are residents of congregate living settings; and
 belong to racialized and/or marginalized communities disproportionately affected by COVID-19.
• NACI has also added a new discretionary recommendation that all other adolescents 12 to 17 years of age may be offered a first booster at least six months after the last dose of their primary series.

For people 12 to 29 years of age who are receiving a booster dose of an mRNA COVID-19 vaccine, the use of the Pfizer-BioNTech Comirnaty COVID-19 booster dose (30 mcg) may be preferred over the use of the Moderna Spikevax COVID-19 booster dose (50 mcg) due to lower reported rates of myocarditis and pericarditis with the Pfizer-BioNTech Comirnaty COVID vaccine.

People who are moderately to severely immunocompromised who have received a three-dose primary series and pregnant and breastfeeding adults are included in those who may receive a booster dose.

If offering the Moderna Spikevax COVID-19 vaccine as a booster dose, the following doses may be preferred, based on the discretion of healthcare providers:

• 100 mcg: Adults living in long-term care homes for seniors or other congregate living settings that provide care for seniors
• 100 mcg: Adults 70 years of age or older
• 50 mcg: Adults 30 to less than 70 years of age

The Novavax Nuvaxovid vaccine may be offered as a booster dose at least 6 months after completion of a primary vaccine series to adults who are unable or unwilling to receive an mRNA COVID-19 vaccine for a booster. This is considered off-label advice as Novavax Nuvaxovid is not currently authorized for use as a booster in Canada.

Second booster doses

In the context of protection against severe disease potentially decreasing over time following the first booster dose, and/or risk of immune evasion by highly transmissible variants of concern which can cause severe disease:

1. NACI recommends that jurisdictions prepare for the rapid deployment of a second COVID-19 vaccine booster dose program over the coming weeks prioritizing the following populations, as close surveillance and assessment suggest concerning trends in the COVID-19 pandemic:
   a. Adults 80 years of age and over living in the community; and
   b. Residents of long-term care or other congregate living settings for seniors.

While the greatest benefit is expected in adults 80 years of age and older, jurisdictions may also consider offering a second COVID-19 booster dose to adults 70-79 years of age living in the community.

A second booster dose for adults younger than 70 years of age in or from First Nations, Métis, or Inuit communities may be considered. Decisions should be made by Indigenous Peoples with the support of healthcare and public health partners.

In general, jurisdictions should aim to offer second booster doses 6 months after a first booster dose. A 6 month interval may need to be balanced with local epidemiology, which may indicate the need for shorter intervals in order to prevent severe disease. Timing since COVID-19 infection should also be considered for those who have been infected with the SARS-CoV-2 virus. NACI suggests individuals who been infected with the SARS-CoV-2 virus receive a booster dose three months after testing positive or having symptoms or at least 6 months after receiving a first booster dose, whichever duration is longer. 

While not recommended at this time, the planning and deployment of a second COVID-19 booster dose program for other high-risk groups and the general population may be needed in the future if surveillance and assessment suggest concerning trends in the COVID-19 pandemic. Planning should take into account that vaccine deployment may be required for broader population groups in the fall of 2022 or earlier depending on the COVID-19 pandemic context.

Recommendations for second booster doses are off-label, as COVID-19 vaccines are not authorized for use as second booster doses in Canada at this time.

COVID-19 vaccination following SARS-COV-2 infection

NACI continues to recommend that COVID-19 vaccines should be offered to individuals with previous SARS-CoV-2 infection without contraindications to the vaccine. While infection alone provides some protection, vaccination after infection is important to provide the best long-term protection from infection including from current and future variants. Longer intervals between infection and a COVID-19 vaccine dose may help to ensure durable immune responses after vaccination and longer-lasting protection against Omicron and future variants.

At this time, NACI suggests that individuals who experienced SARS-CoV-2 infection before starting or completing their primary COVID-19 vaccine series may receive their next dose 8 weeks after symptoms started or after testing positive (if no symptoms were experienced).

For individuals who have contracted COVID-19 and are recommended to receive a booster dose, NACI suggests a 3-month interval between infection and a booster dose (i.e., 3 months after symptom onset or positive test if asymptomatic) or 6 months from the most recent vaccine dose, whichever is longer.

Key Facts
• The National Advisory Committee on Immunization (NACI) is an external body of experts that provides recommendations to the Public Health Agency of Canada on the use of authorized COVID-19 vaccines to support provinces and territories in planning COVID-19 vaccine programs in Canada.