Canadian influenza vaccine guidelines for 2023-24 are now available

The National Advisory Committee on Immunization (NACI) has released the influenza vaccine guidelines for the 2023-24 flu season. As in the past, Canadian healthcare providers are advised to offer seasonal influenza vaccine as soon as possible after it becomes available in the fall, since seasonal influenza activity may start as early as October in the Northern Hemisphere. The 2023-24 guidelines continue to focus on key information for vaccine providers. This includes “what, who, how and why” for influenza/influenza vaccine; epidemiology of influenza; vaccine products authorized for use in Canada; efficacy, effectiveness and immunogenicity of influenza vaccines; vaccine administration; storage requirements; concurrent administration with other vaccines; vaccine safety and adverse events; choice of seasonal influenza vaccine (including a concise summary table organized by age group); and particularly recommended vaccine recipients. NACI recommends offering influenza vaccine annually to anyone six months of age or older who does not have a contraindication to the vaccine. Priority should be placed on the groups for whom influenza vaccination is particularly recommended. These include people at high risk of severe disease, influenza-related complications or hospitalization; people capable of transmitting influenza to those at high risk; people who provide essential community services; and people in direct contact with poultry infected with avian influenza during culling operations. New or updated information in the 2023–2024 influenza vaccine guidelines: COVID-19 A statement on the use of seasonal influenza vaccine in the context of COVID-19 was updated on Feb. 6, 2023. It should be considered in conjunction with NACI’s recommendations on the use of seasonal influenza vaccines. Guidance on concurrent administration of influenza and COVID-19 vaccines. Administration of COVID-19 vaccines may occur at the same time as, or at any time before or after influenza immunization (including all parenteral or intranasal seasonal influenza vaccines) for those aged six months of age or older. Flucelvax Quad Recommendations have been updated on the use of mammalian cell culture-based quadrivalent influenza vaccine (Flucelvax Quad). This standard dose mammalian cell culture-based quadrivalent inactivated seasonal influenza vaccine was first authorized for use in Canada in adults and children nine years of age and older on November 22, 2019. Authorization was extended to children two years of age or older on March 8, 2021. Recommendations and supporting evidence on the use of Flucelvax Quad in adults and children two years of age or older were incorporated into NACI’s influenza guidelines in 2022–2023. On March 8, 2022, Health Canada approved an expanded age range for the use of Flucelvax Quad in children to now include children six months of age or older. NACI concluded that Flucelvax Quad is safe and has noninferior immunogenicity compared to standard quadrivalent inactivated influenza vaccines. Therefore, NACI recommends that Flucelvax Quad may be considered among the quadrivalent influenza vaccines offered to adults and children six months of age or older (Discretionary NACI recommendation). Influvac Tetra Recommendations have been updated on the use of the egg-based quadrivalent influenza vaccine, Influvac Tetra. This split virus standard quadrivalent inactivated influenza vaccine was first authorized for use in Canada in adults on March 1, 2019 and subsequently in children three years of age or older on February 20, 2020. Recommendations and supporting evidence on the use of Influvac Tetra in adults and children three years of age and older were incorporated into NACI’s influenza guidelines in 2021–2022. On November 30, 2021, Health Canada approved an expanded age range for Influvac Tetra to include children six months of age or older. NACI concluded that Influvac Tetra appears to be safe and well tolerated in children six to 35 months of age. However, evidence is currently insufficient on whether Influvac Tetra is effective and elicits a protective immune response against seasonal influenza in children six to 35 months of age. Therefore NACI recommends that Influvac Tetra may be considered among the standard dose inactivated quadrivalent influenza vaccines offered to individuals three years of age or older (Discretionary NACI recommendation). Evidence is insufficient for recommending vaccination with Influvac Tetra in children younger than three years of age. Trivalent formulations All standard dose, egg-based inactivated influenza vaccines authorized and available in Canada for the 2023–2024 season are expected to be quadrivalent formulations. No trivalent formulations are expected to be marketed in Canada for the 2023/24 influenza season. Appendix B (pg. 61–62 of the guidelines) summarizes the characteristics of influenza vaccines available for use in Canada in 2023–2024, including vaccine type, route of administration, authorized ages for use, antigen content for each vaccine strain, adjuvant, formats available, postpuncture shelf-life for multidose vials, thimerosal content, antibiotic (trace) content, and production medium (e.g., egg). NACI stresses that annual influenza vaccination is required because the specific strains in the vaccine are reviewed each year by the World Health Organization and are often changed to provide a better match against the viruses expected to circulate in that given year. In addition, the body’s immune response to influenza vaccination may be transient and may not persist beyond a year. Reference 1. National Advisory Committee on Immunization (NACI). An Advisory Committee Statement (ACS). Statement on seasonal influenza vaccine for 2023-2024. (accessed June 6, 2023).

Canadian influenza vaccine guidelines for 2023-24 are now available

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