Revised: 10 November 2025

Medicines

Influenza Vaccine Composition

Trivalent vaccines
Quadrivalent vaccines
Candidate vaccine viruses
Background to the recommendations
Approval process for seasonal composition updates

The Australian Influenza Vaccine Committee (AIVC), with a New Zealand representative, met to consult on the influenza vaccine composition for 2026 for New Zealand, Australia and South Africa in October 2025. The information below describes the AIVC recommendation.

Trivalent vaccines

For trivalent vaccines for use in the 2026 southern hemisphere influenza season: 

Egg-based vaccines 

• an A/Missouri/11/2025 (H1N1)pdm09-like virus;
• an A/Singapore/GP20238/2024 (H3N2)-like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage) - like virus.

Cell-based, recombinant-based or nucleic acid-based vaccines

• an A/Missouri/11/2025 (H1N1)pdm09-like virus;
• an A/Sydney/1359/2024 (H3N2)-like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

The continued absence of confirmed detection of naturally occurring B/Yamagata lineage viruses after March 2020 is indicative of a very low risk of infection by B/Yamagata lineage viruses. Consistent with the previous four WHO recommendations since September 2023, it remains the opinion of the WHO influenza vaccine composition advisory committee that inclusion of a B/Yamagata lineage antigen is no longer warranted. There will no longer be updated recommendations for the B/Yamagata lineage component. The AIVC supports this position.

Quadrivalent vaccines

For quadrivalent vaccines, where the transition to trivalent vaccines is not yet complete, the 4th component is a B/Yamagata lineage virus. Although not included in the AIVC recommendation, the WHO recommends B/Phuket/3073/2013-like virus for the B/Yamagata strain, unchanged from the 2025 southern hemisphere influenza season.

Candidate vaccine viruses

Candidate vaccine viruses (CVV) recommended for H1N1 and H3N2 are different for egg- and cell-based vaccines as, in some instances, the same virus is not optimal for both production systems. When this is the case, different viruses with similar properties are selected as the prototypes to facilitate timely vaccine production. For more information, see the Questions and Answers document (PDF, 229 KB, 8 pages), published on the World Health Organization's (WHO) website.

For the CVV recommended for the 2026 southern hemisphere influenza season, see the WHO's vaccine viruses and reagents web pages.

Background to the recommendations

The recommended influenza vaccine composition is based on the outcome of:

• the meeting of the AIVC, with a New Zealand representative, to consult on the influenza vaccine composition for 2026 (held on 8 October 2025). Refer to PHF Science Influenza vaccine recommendations report for 2026 for the AIVC recommendation, as well as information regarding epidemiology and recent strain characterisations in New Zealand
• information on international surveillance by the WHO Global Influenza Surveillance and Response System
• analysis of recent data on epidemiology and strain characterisation
• the recommendations of the WHO annual consultation on the composition of 2026 influenza vaccines for the southern hemisphere.

Approval process for seasonal composition updates

Sponsors wanting to introduce seasonal composition updates for approved influenza vaccines must obtain approval via the following two-stage CMN process:

Stage 1: A CMN (Form B; change category Labelling - G2) to update labelling and product literature. This CMN must include a commitment to not distribute affected product until a relevant CMN (see Stage 2 below) to update the formulation has been consented. The data sheet/CMI will not be published on the Medsafe website until the formulation change has been approved; however, the sponsor can provide the updated literature to healthcare professionals and relevant stakeholders directly, once it has been approved by Medsafe.

Stage 2: A CMN (Form B; change category Formulation - G1) for approval of the updated formulation. This CMN to update the vaccine formulation (with regards to virus strains) should include the following information (and can be submitted as a rolling submission).

• Summarised quality control information for Master and Working Seed Lots proposed for use in the forthcoming campaign, including strain history, and results from testing for sterility, mycoplasma, identity of haemagglutinin and neuraminidase, and egg infectivity. If results from genetic analysis are not available, sponsors should provide an estimated date for the provision of this data.
• An assessment of the risks of contamination of the product with extraneous agents, updated as relevant with regards to new or emerging viruses potentially present in materials or clinical isolates used to generate the new seeds.
• Batch analysis data (including verification of HA and NA, and validation of splitting/solubilisation (as relevant) and inactivation) for three monovalent pooled harvest batches made at commercial scale using the proposed seeds. Data should be compared to relevant compendial monograph requirements. Sponsors should also provide particle size analysis for new strains.
• Qualification of SRD testing of HA content in drug substance and drug product using defined standard antigens and antisera. Demonstration of specificity of B-strain reagents should include evidence for a lack of cross-reactivity between the B-strain viruses from the quadrivalent product.
• Stability data from testing of drug substances and drug product in recent years to support the proposed shelf life for the forthcoming campaign, along with a protocol to monitor stability of drug substances and drug product from the forthcoming campaign. Sponsors should also provide any stability data obtained to date from the forthcoming campaign, and a commitment to inform Medsafe of OOS results or aberrant trends that may arise.
• Confirmation that the product is in full compliance with a relevant Ph. Eur. monograph for influenza vaccine (specify which monograph).
• Data from release testing of three batches of SH finished product from the forthcoming season, or a commitment to forward this as soon as available.
• Commitment to provide Medsafe with Certificates of Analysis for the first three vaccine lots intended for the New Zealand market in the forthcoming season prior to their distribution.
• If the updated data sheet and CMI have been approved by Medsafe (as part of Stage 1) then this should be highlighted in the cover letter. Otherwise, the updated documents should be included in this CMN using the relevant data sheet change category.

For further guidance about these information requirements, see the European Medicines Agency document, EMA/CHMP/BWP/310834/2012 Guideline on Influenza Vaccines - Quality Module (PDF, 356 KB, 34 pages).