Bivalent Omicron-containing mRNA COVID-19 vaccines are authorized as booster doses for those 5 years of age and older, but there is currently no bivalent vaccine authorized for a primary series in any age group or as a booster dose for those less than 5 years of age. Several regulatory submissions for the use of bivalent mRNA COVID-19 vaccines as a primary series are currently under review by Health Canada. Many original monovalent mRNA vaccines will no longer be available in the coming months, and PHAC has asked NACI to consider how jurisdictions can ensure COVID-19 product options for the primary series are available to all recommended populations. This includes consideration of off-label use of bivalent vaccines using age-based dosages that are different from those currently authorized for the primary series with the original mRNA COVID-19 vaccines. As regulatory submissions progress over the summer, vaccine schedules and/or dosages may change for some age groups. New formulations of COVID-19 vaccines that reflect changes in circulating Omicron subvariants may also become available in the fall of 2023.

Bivalent Omicron-containing mRNA COVID-19 vaccines have been recommended to be used as booster doses in Canada since September 1, 2022, when NACI published initial recommendations on their use. Currently, bivalent Omicron-containing vaccines are authorized as booster doses for individuals 5 years of age and older and NACI’s recommendations cite a preference for their use over original mRNA vaccines for booster doses. For more information on COVID-19 booster doses, please refer to the COVID-19 chapter of the Canadian Immunization Guide (CIG).

Since the initial authorization and recommendations of bivalent Omicron-containing COVID-19 vaccine booster doses:

  • Although there are some fluctuations in COVID-19 transmission indicators (i.e., cases reported, hospitalizations, and deaths) and variations across provinces and territories, COVID-19 activity has been relatively stable with hospitalizations remaining at a relatively high level since the widespread circulation of Omicron in early 2022, with the highest hospitalization rates among older adults.
  • Additional evidence has emerged on the performance and safety of bivalent vaccines as booster doses.
  • Some limited direct evidence is now available on the use of bivalent Omicron-containing vaccines for the primary series.

NACI continues to monitor the rapidly evolving scientific data recognizing that the trajectory of the COVID-19 pandemic remains unclear. NACI's recommendations remain aligned with the goals of the Canadian COVID-19 Pandemic Response that were last updated on February 14, 2022:

  • To minimize serious illness and death while minimizing societal disruption as a result of the COVID-19 pandemic
  • To transition away from the crisis phase towards a more sustainable approach to long term management of COVID-19
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