In September 2023, the World Health Organization (WHO) released recommendations for the 2024 Southern Hemisphere influenza season, endorsing the exclusion of the B/Yamagata lineage antigen from influenza vaccine formulations due to the global absence of circulating B/Yamagata viruses since March 2020Footnote1. This recommendation was repeated in February 2024 for the 2024-2025 Northern Hemisphere influenza seasonFootnote2. In March 2024, the United States (US) Food and Drug Administration (FDA) Vaccines and Related Biological Products Advisory Committee (VRBPAC) decided to exclude B/Yamagata in their strain recommendations for the 2024-2025 Northern Hemisphere influenza season and transition to trivalent influenza vaccines for the 2024-2025 seasonFootnote3. In the same month, the European Medicines Agency (EMA) in the European Union (EU) also recommended the removal of B/Yamagata from all live-attenuated influenza vaccines (LAIVs) ideally for the 2024-2025 season, with a transition to trivalent composition for all other influenza vaccines to be completed by the 2025-2026 seasonFootnote4.
Historically, quadrivalent influenza vaccines containing strains from both influenza B lineages (B/Victoria and B/Yamagata) have been in use in Canada since the 2014-2015 seasonal influenza vaccination campaign to provide broader protection against circulating influenza B viruses. Children experience a higher burden of disease due to influenza B infection compared to other age groups, and quadrivalent formulations have previously been preferentially recommended for children in Canada to provide more protection against B strains. All seasonal influenza vaccines currently available in Canada are quadrivalent, other than adjuvanted vaccines, which are available only in trivalent formulations. Further information on characteristics of influenza vaccines available for use in Canada is available in Appendix B of the 2024-2025 influenza seasonal statementFootnote5.
The objective of this advisory committee supplemental statement is to describe anticipated updates to influenza vaccine formulations, acknowledging and highlighting:
- the new WHO, US FDA VRPBAC, and EU EMA recommendations to remove the B/Yamagata strain from vaccine formulations;
- the public health implications; and
- the resultant changes to the National Advisory Committee on Immunization (NACI) seasonal influenza guidance.
- Recommendation
- Americas
- Canada
- Influenza
