What is the latest influenza (flu) vaccine available?

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Last updated: September 5, 2025 • View editorial policy

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Latest Influenza Vaccine for 2024-2025 Season

The latest influenza vaccine available for the 2024-2025 season is Fluzone, which contains the updated strains A/Victoria/4897/2022 (H1N1), A/California/122/2022 (H3N2), and B/Michigan/01/2021 (B Victoria lineage). 1

Current Vaccine Composition

The 2024-2025 Fluzone vaccine contains the following influenza strains:

  • A/Victoria/4897/2022 IVR-238 (H1N1)
  • A/California/122/2022 SAN-022 (an A/Thailand/8/2022-like virus) (H3N2)
  • B/Michigan/01/2021 (a B/Austria/1359417/2021-like virus, B Victoria lineage)

This represents the most current formulation based on the FDA-approved labeling 1.

Available Vaccine Types

For the most recent complete season with published guidelines (2022-2023), the following types of influenza vaccines were available 2:

Inactivated Influenza Vaccines (IIVs):

  • Standard-dose quadrivalent (IIV4)
  • Cell culture-based quadrivalent (ccIIV4)
  • High-dose quadrivalent (HD-IIV4) for adults ≥65 years
  • Adjuvanted quadrivalent (aIIV4) for adults ≥65 years

Other Platforms:

  • Recombinant quadrivalent (RIV4)
  • Live attenuated influenza vaccine quadrivalent (LAIV4)

Evolution of Influenza Vaccines

There has been a clear progression in influenza vaccine development over recent years:

  • Transition from trivalent to quadrivalent formulations to provide broader protection against both B virus lineages (Victoria and Yamagata) 3
  • Development of specialized formulations for older adults (high-dose and adjuvanted vaccines) 2
  • Introduction of cell culture-based and recombinant vaccines as alternatives to egg-based production 2

Key Considerations for Vaccine Selection

While all available vaccines are considered effective, certain populations may benefit from specific formulations:

  • Adults ≥65 years: High-dose or adjuvanted formulations are specifically designed to enhance immune response in older adults
  • Egg allergy: Cell culture-based (ccIIV4) or recombinant (RIV4) vaccines may be preferred
  • Children 6 months to 8 years: May require two doses if they have not previously received ≥2 doses of influenza vaccine

Common Pitfalls to Avoid

  1. Outdated information: Influenza vaccine compositions change annually based on predicted circulating strains
  2. Assuming all vaccines are equivalent: Different formulations exist for different age groups and populations
  3. Delaying vaccination: The CDC recommends getting vaccinated before the end of October, though vaccination throughout the influenza season is beneficial

The Fluzone vaccine for the 2024-2025 season represents the most current formulation available, containing updated viral strains selected to match those predicted to circulate during the upcoming influenza season 1.

References

2
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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