Updates on Influenza vaccine strain recommended by WHO (2025–2026 northern hemisphere)

Written by Sino Biological
Company news

Here are the 2025–2026 northern hemisphere Influenza vaccine strain updates.

To maintain vaccine efficacy, WHO regularly updates influenza vaccine strains based on global epidemiological, virological and serological analyses. On 28 February 2025, WHO announced the recommended strains for the 2025–2026 northern hemisphere influenza season1:

    1. Trivalent egg-based vaccines
      • an A/Victoria/4897/2022 (H1N1) pdm09-like virus
      • an A/Croatia/10136RV/2023 (H3N2)-like virus
      • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus
    1. Trivalent cell culture- or recombinant protein-based vaccines
      • an A/Wisconsin/67/2022 (H1N1) pdm09-like virus
      • an A/District of Columbia/27/2023 (H3N2)-like virus
      • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus
    1. Quadrivalent egg- or cell culture/recombinant-based vaccines (unchanged from 2024)
      • a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus

Comparison of 2024–2025 vs. 2025–2026 vaccine components

Table 1. Key updates of influenza vaccine composition for the 2025–2026 northern hemisphere influenza season.

Vaccine type 2024–2025 strains 2025–2026 updated strains Key changes
Trivalent egg-based A/Thailand/8/2022 (H3N2) A/Croatia/10136RV/2023 (H3N2) H3N2 strain substituted
Trivalent cell/recombinant A/Massachusetts/18/2022 (H3N2) A/District of Columbia/27/2023 (H3N2) H3N2 strain substituted
Quadrivalent Tri-valent + B/Phuket/3073/2013* Tri-valent + B/Phuket/3073/2013* B/Yamagata lineage retained*
    1. H3N2 strain substitution
      • Egg-based vaccines: 2022 strain (A/Thailand/8/2022) substituted with A/Croatia/10136RV/2023 (H3N2)
      • Cell/recombinant vaccines: 2022 strain (A/Massachusetts/18/2022) substituted with A/District of Columbia/27/2023 (H3N2)
    2. No changes to H1N1 or B/Victoria Lineage
      • H1N1 strains (egg: A/Victoria/4897/2022; cell/recombinant: A/Wisconsin/67/2022) and B/Victoria lineage (B/Austria/1359417/2021) remain unchanged
    3. Summary
      • Core change: updated H3N2 strains reflect their high mutation rate
      • Continuous development: consecutive adjustments to H3N2 highlight the need for rapid vaccine adaptation to viral evolution

Recombinant antigens: critical materials for vaccine research

Table 2. Key target antigens (HA, NA, NP) play vital roles in influenza vaccine, drug and diagnostic development.

Protein Function Applications
HA (Hemagglutinin) Binds to host cell receptors, mediates viral entry Vaccine development, neutralizing antibody research, diagnostic reagents
NA (Neuraminidase) Cleaves sialic acid receptors to release viral particles Antiviral drug development, vaccine optimization, diagnostic kits
NP (Nucleoprotein) Binds viral RNA, supports replication and genome stability Broad-spectrum antiviral research, diagnostic product development

Applications of recombinant antigens:

  • Vaccine development: used in potency testing, ELISA-based antibody level analysis and quality control
  • Research acceleration: replace traditional viral culture methods, shortening R&D timelines

Figure 1. Recombinant HA protein used to measure serum antibody levels in vaccinated mice 2.

Sino Biological unveils comprehensive Influenza research reagents for 2025–2026 vaccine strains

Sino Biological, a leading provider of biological reagents and services, has announced the release of its latest portfolio of influenza research reagents. Designed to support the development of vaccines for the 2025–2026 northern hemisphere influenza season, the new offerings include high-quality recombinant HA, NA and NP proteins. These reagents are now available for immediate order, providing researchers with the tools they need to accelerate their studies and contribute to global influenza prevention efforts. For more details, please visit our website: www.sinobiological.com.

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About Sino Biological
Sino Biological is a global leader in protein and antibody research, specializing in the production of high-quality recombinant proteins and antibodies for life sciences research and innovative drug development. Headquartered in Beijing, Sino Biological was listed on the Shenzhen Stock Exchange’s ChiNext board in August 2021 (stock code: 301047). As a national high-tech enterprise, the company has developed five core technology platforms, advancing biological reagent research centered around proteins and antibodies. Sino Biological offers over 74,000 stocked products, including nearly 9000 recombinant proteins, 14,000+ antibodies, 50,000 genes and a series of high-performance serum-free media products. The company also operates a one-stop CRO service platform covering gene cloning, protein expression, antibody development, production and quality control research. With its expertise, Sino Biological has successfully developed complex reagents, such as full-length membrane proteins, kinases, phosphorylated antibodies and GMP-grade cytokines, establishing the world’s leading recombinant protein and antibody library based on human cell expression.

Source

  1. World Health Organization. Recommendations announced for influenza vaccine composition for the 2025–2026 northern hemisphere influenza season. Published 28 February 2025.
  2. Andersen TK, Bodin J, Oftung F, Bogen B, Mjaaland S, Grødeland G. Pandemic preparedness against Influenza: DNA vaccine for rapid relief. Front. Immunol. 12, 747032 (2021).