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Summary of updates in the Canadian Immunization Guide as of June 27, 2023: Updated guidance on COVID-19 vaccines in Canada 

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Overview

On June 27, 2023, the Public Health Agency of Canada (PHAC) released updated guidance from the National Advisory Committee on Immunization (NACI) on the use of COVID-19 vaccines in the COVID-19 vaccine chapter of the Canadian Immunization Guide (CIG). This guidance is based on current evidence and/or NACI's expert opinion.

What you need to know

The COVID-19 vaccine chapter was revised based on the following updated guidance:

  1. Guidance on the use of Moderna bivalent BA.1 and BA.4/5 as a booster dose in individuals 6 to 17 years of age
  2. Guidance on the use of Novavax Nuvaxovid COVID-19 vaccine as a primary series in individuals 12 years of age and older and as a booster dose for adults 18 years of age and older

Supporting information

1. Guidance on the use of Moderna bivalent BA.1 and BA.4/5 as a booster dose in individuals 6 to 17 years of age

NACI was asked to issue guidance on the use of Moderna Spikevax® Bivalent COVID-19 vaccines as a booster dose in children and adolescents 6 to 17 years of age. At the time, only Moderna Spikevax® Bivalent COVID-19 vaccine (Original/Omicron BA.1) was authorized as a booster dose in children 6 to 11 years of age (25 mcg dose) and adolescents 12 to 17 years of age (50 mcg dose). Subsequently, Health Canada approved the use of Moderna Spikevax Bivalent COVID-19 vaccine (Original/Omicron BA.4/5) for individuals 6 years of age and older.

NACI recommends the use of Moderna Spikevax® Bivalent COVID-19 vaccines (Original/Omicron BA.1 and Original/Omicron BA.4/5) as a booster dose for individuals 6 to 17 years of age.

While there were no direct clinical data on the use of Moderna Spikevax® Bivalent COVID-19 vaccines in individuals 6 to 17 years of age, indirect evidence from adult populations has been summarized in earlier NACI statements. Emerging evidence suggests the vaccine effectiveness of bivalent boosters is at least as good, and possibly better than that of original vaccines, although data on the duration of protection are limited. Post-market safety data have shown comparable safety profiles between the original and bivalent formulations of the Moderna Spikevax® COVID-19 vaccine as booster doses.

NACI has also recommended that individuals receiving a booster dose can receive either a Moderna Spikevax® (6 years of age and older) or Pfizer Comirnaty® (5 years of age and older) mRNA COVID-19 vaccine product. Bivalent vaccines continue to be the preferred product for booster doses at this time.

NACI reviewed additional data on the risk of myocarditis and/or pericarditis following the use of the original and bivalent formulations of the Moderna Spikevax® COVID-19 vaccine. Evidence from bivalent and original mRNA COVID-19 vaccines across different age groups show that the risk of myocarditis is lower following booster doses 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. However, while these observations included adolescents 12 to 17 years of age, the use of Moderna Spikevax® COVID-19 vaccines has been limited in children and adolescents 5 to 17 years of age. NACI will continue to monitor post-market safety surveillance data as it emerges and update its recommendations as needed.

This guidance was approved by NACI on March 7, 2023. The Moderna Spikevax Bivalent COVID-19 vaccine (Original/Omicron BA.4/5) was authorized as a booster dose for individuals aged 6 years and older on May 18, 2023.

Provided is a list of selected references that informed this guidance:

2. Guidance on the use of Novavax Nuvaxovid COVID-19 vaccine as a primary series in individuals 12 years of age and older and as a booster dose for adults 18 years of age and older

The updated recommendation on primary series is based on clinical trial evidence on a primary series with Novavax Nuvaxovid in adolescents 12 to 17 years of age, and indirect post-market vaccine effectiveness and safety data in adults.

The updated booster recommendation is based on clinical trial evidence on the immunogenicity and safety of Novavax Nuvaxovid as a homologous booster dose following a primary series with Nuvaxovid and as a heterologous booster following a primary series with another COVID-19 vaccine, as well as post-market evidence on booster dose effectiveness and safety.

The continued preferential recommendation for the use of mRNA COVID-19 vaccines over Novavax Nuvaxovid is due to the availability of substantially more data regarding the benefits and risks of mRNA COVID-19 vaccines compared to the amount of data yet available for Novavax Nuvaxovid. Novavax Nuvaxovid remains a strong option that should be offered as recommended to those who are not able or willing to receive an mRNA COVID-19 vaccine.

Primary series

NACI had previously recommended that a primary series of Novavax Nuvaxovid may be offered to adults 18 years of age and older who are not willing or able to receive an mRNA COVID-19 vaccine.

On December 6, 2022, Health Canada authorized Novavax Nuvaxovid COVID-19 vaccine for use as a primary series in adolescents 12 to 17 years of age. In response to this authorization and after reviewing available evidence, NACI has now strengthened and expanded the recommendation such that a primary series of Novavax Nuvaxovid should be offered to individuals 12 years of age and older without contraindications to the vaccine who are not able or willing to receive an mRNA COVID-19 vaccine. A primary series consists of 2 doses of 5 mcg (0.5 mL) given at an optimal interval of 8 weeks apart. An extra dose of Novavax Nuvaxovid is not currently authorized for individuals who are moderately to severely immunocompromised. However, based on clinical discretion, NACI recommends that Novavax Nuvaxovid should be offered as a 3-dose primary series to moderately to severely immunocompromised individuals who are not able or willing to receive an mRNA COVID-19 vaccine, at a recommended interval of 4 to 8 weeks between doses.

Boosters

On November 17, 2022, Health Canada authorized the use of Novavax Nuvaxovid as a homologous booster dose in individuals 18 years of age and older, to be administered approximately 6 months after the completion of the second dose of the primary series.

NACI had previously issued guidance on the off-label use of Novavax Nuvaxovid as a booster for adults 18 years of age and older on February 17, 2022. Following its review of additional data, NACI has now strengthened this recommendation and now recommends that a booster dose of Novavax Nuvaxovid should be offered to adults 18 years of age and older without contraindications to the vaccine who are not able or willing to receive an mRNA COVID-19 vaccine.

Cases of myocarditis and/or pericarditis have been rarely reported following the administration of Novavax Nuvaxovid. In Australia, over 251,000 doses of Novavax Nuvaxovid have been administered as of April 16, 2023. Australia's Therapeutic Goods Administration (TGA) reported that after any dose of Novavax Nuvaxovid, myocarditis has been reported at a rate of approximately 3 or 4 per 100,000 recipients and pericarditis has been reported at rate of 13 per 100,000 recipients. A further breakdown of the rates of myocarditis and/or pericarditis after Novavax Nuvaxovid 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 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 have been administered as of December 31, 2022, with no reported cases of myocarditis. In Canada, there have been no reported cases of myocarditis and/or pericarditis following Novavax Nuvaxovid as of March 26, 2023 (following approximately 32,200 doses administered).

This guidance was approved by NACI on April 28, 2023.

Provided is a list of selected references that informed this guidance:

For more information on NACI's recommendations on the use of COVID-19 vaccines, please refer to the COVID-19 vaccine chapter in the Canadian Immunization Guide (CIG), as well as additional statements on the NACI web page.

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