2024-02-22-世界卫生组织-Recommended_composition_of_influenza_virus_vaccines_for_use_in_the_2024-2025_northern_hemisphere_influenza_season_9页_380kb

Summary of WHO Recommended Influenza Vaccine Composition for 2024-2025 Northern Hemisphere Season

Purpose

The World Health Organization (WHO) convened technical consultations in February 2024 to recommend influenza viruses for inclusion in vaccines for the 2024-2025 northern hemisphere influenza season. This recommendation is based on surveillance data from September 2023 to January 2024.

Seasonal Influenza Activity

From September 2023 to January 2024, global influenza activity was generally similar to the same period in 2023. Influenza A viruses predominated worldwide, with A(H1N1)pdm09 being the most common subtype. Influenza B viruses were less frequent but were mostly of the B/Victoria lineage. Specific regional variations were noted:

• Africa: A(H1N1)pdm09 dominated, with co-circulation of A(H3N2) and B/Victoria in some areas.
• Asia: High activity in December, with A(H3N2) predominating in Eastern Asia; B/Victoria emerged later.
• Europe: Influenza A dominated, with co-circulation of A(H1N1)pdm09 and A(H3N2); B/Victoria was common in some regions.
• Americas: A(H1N1)pdm09 was predominant in North and Central America; in Temperate South America, A became predominant in December.
• Oceania: Low activity overall, with co-circulation of A(H1N1)pdm09 and A(H3N2), and some B/Victoria.

Influenza A

• A(H1N1)pdm09: Circulated globally and was the predominate virus in most regions. Genetic analysis showed it belonged to clade 6B.1A.5a.2, with subclades 5a.2a and 5a.2a.1. Antigenic testing showed good recognition by post-vaccination sera.
• A(H3N2): Predominated in many regions, with subclade 2a.3a.1 being the most common. Some recent viruses showed reduced recognition by ferret antisera and human sera, but no significant reduction in vaccine effectiveness was confirmed.

Influenza B

• Globally, the B/Victoria lineage was the only circulating influenza B virus since March 2020, with no B/Yamagata detections.
• Genetic analysis indicated that the HA genes belonged to subclade 3a.2, which has diversified but remains well-recognized by vaccines.
• WHO recommends excluding the B/Yamagata lineage from vaccines as it is no longer circulating.

Recommended Vaccine Composition

For the 2024-2025 northern hemisphere influenza season, WHO recommends the following strains:

• Egg-based vaccines:
  • A/Victoria/4897/2022 (H1N1)pdm09-like virus.
  • A/Thailand/8/2022 (H3N2)-like virus.
  • B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
• Cell culture or recombinant-based vaccines:
  • A/Wisconsin/67/2022 (H1N1)pdm09-like virus.
  • A/Massachusetts/18/2022 (H3N2)-like virus.
  • B/Austria/1359417/2021 (B/Victoria lineage)-like viru.