NACI releases statement on seasonal influenza vaccine for 2024–25

The National Advisory Committee on Immunization has published a statement on seasonal influenza vaccine for 2024–2025. The document provides comprehensive information for vaccine providers, including vaccine products authorized for use in Canada; 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 a list of particularly recommended vaccine recipients.1New or updated information for 2024–2025 is summarized below:Updated recommendations on the use of influenza vaccines during pregnancy. A supplemental statement (November 2023) provided updated guidance on influenza vaccination during pregnancy. Evidence supports the safety and effectiveness of influenza vaccines during pregnancy. NACI continues to strongly recommend that inactivated or recombinant influenza vaccines be offered during pregnancy, at any gestational age. Pregnant individuals continue to be on the list of individuals for whom influenza vaccination is particularly important. NACI also reaffirmed that influenza vaccine may be given at the same time as, or at any time before or after administration of another vaccine, including COVID-19 or pertussis vaccine.1 Updated recommendations on the use of influenza vaccines in older adults. On May 31, 2024, NACI released supplemental guidance on influenza vaccination in adults 65 years of age or older.2 NACI continues to include adults 65 years of age or older among those for whom influenza vaccination is particularly important, because of their increased risks of severe disease. The supplemental statement provides an evidence summary on the preferential use of one or more of the age-appropriate influenza vaccines in adults 65 years of age and older. Overall, the evidence supports high-dose inactivated influenza vaccine (Fluzone High-Dose Quadrivalent), adjuvanted inactivated influenza vaccine (Fluad) and recombinant influenza vaccine (Supemtek) as having increased benefits as compared to standard-dose inactivated influenza vaccines, with no difference in safety. NACI strongly recommends that one of these three vaccines (Fluzone High-Dose Quadrivalent, Fluad or Supemtek) should be offered, when available, over other influenza vaccines for adults 65 years of age and older. If a preferred product is not available, any of the available age-appropriate influenza vaccines should be used.1,2Transitioning from quadrivalent to trivalent flu vaccines. NACI issued an addendum to the 2024-2025 statement on seasonal influenza vaccine to explain the anticipated transition from quadrivalent to trivalent influenza vaccines. The transition stems from the World Health Organization (WHO) endorsement of the exclusion of the B/Yamagata lineage antigen from influenza vaccine formulations, due to the absence of circulating B/Yamagata viruses globally since March 2020. A transition from quadrivalent to trivalent influenza vaccines, with exclusion of the B/Yamagata strain, is already underway in the United States and the European Union.3 NACI notes that for the 2024-2025 influenza season in Canada, vaccine availability is anticipated to remain unchanged. Quadrivalent formulations will continue to be supplied for public programs. No trivalent formulations will be available for standard dose or high-dose inactivated influenza vaccines or live-attenuated influenza vaccine, while adjuvanted inactivated influenza vaccines will remain trivalent and continue to be available in Canada.3 However, transition from quadrivalent to trivalent flu vaccines is anticipated for Canada in 2025–2026.Flu vaccine preference for children. Quadrivalent influenza vaccines containing strains from both influenza B lineages (B/Victoria and B/Yamagata) have been used in Canada since 2014-2015, to provide broader protection against circulating influenza B viruses. As children experience a higher burden of disease due to influenza B infection compared to other age groups, quadrivalent formulations have been preferentially recommended for children in Canada to provide more protection against B strains. However, with the absence of circulating B/Yamagata viruses globally since March 2020 and the planned transition from quadrivalent to trivalent flu vaccines, NACI now recommends that any age-appropriate quadrivalent or trivalent influenza vaccine should be used for individuals six months of age or older who do not have contraindications or precautions.3 NACI stresses that this updated recommendation for children replaces the information found in the recommendations section (Table 2; Children 6 to 23 months of age; Children 2 to 17 years of age) within the NACI 2024–2025 statement on seasonal influenza vaccine.4Highly pathogenic avian influenza (HPAI) A(H5N1) outbreaks. As of July 2024, multiple outbreaks of highly pathogenic avian influenza A(H5N1) have occurred in poultry and wild birds in Canada and the United States, with spillover events in US dairy cattle. This virus has also spread to numerous other mammals. To date in 2024, nine humans have acquired mild influenza A(H5Nx) infections from cows and poultry in the United States. Healthcare professionals should refer to the Public Health Agency of Canada (https://www.canada.ca/en/public-health/services/diseases/avian-influenza-h5n1/health-professionals.html) for updates on the avian influenza A(H5N1) outbreak. NACI emphasizes its recommendation that all individuals six months of age or older should receive an authorized, age-appropriate seasonal influenza vaccine. This includes those likely to have significant exposure to influenza A(H5N1) through interactions with birds or mammals (e.g., poultry, livestock, slaughterhouse and processing plant workers, wildlife officers/researchers, veterinarians). Seasonal influenza vaccines do not provide protection against infection with influenza A(H5N1) viruses. However, they may reduce the risk of seasonal human and influenza A(H5N1) virus co-infection and possible viral reassortment leading to a human-transmissible virus with pandemic potential.5References:National Advisory Committee on Immunization (NACI). An Advisory Committee Statement (ACS). Statement on seasonal influenza vaccine for 2024–2025. (accessed August 1, 2024).National Advisory Committee on Immunization (NACI). An Advisory Committee Statement (ACS). Supplemental guidance on influenza vaccination in adults 65 years of age and older. (accessed August 1, 2024).National Advisory Committee on Immunization (NACI). An Advisory Committee Statement (ACS). Addendum to the statement on seasonal influenza vaccine for 2024-2025: Transition from quadrivalent to trivalent influenza vaccines. (accessed August 1, 2024).National Advisory Committee on Immunization (NACI). Important notice 1: Update to seasonal influenza vaccine recommendations for 2024-2025. (accessed August 1, 2024).National Advisory Committee on Immunization (NACI). Important notice 2: Outbreaks of highly pathogenic avian influenza in Canada and U.S. (accessed August 1, 2024).

NACI releases statement on seasonal influenza vaccine for 2024–25

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