Austria Adopts Trivalent Flu Vaccine in 2025: Responding to the Disappearance of B/Yamagata

Austria is switching to a trivalent flu vaccine for the 2025/2026 season, reflecting a major international update in influenza vaccination strategy. The vaccine includes three strains (A/H1N1, A/H3N2, and B/Victoria) and drops the B/Yamagata strain, which has not been detected globally since March 2020 and is considered eradicated.ema.europa+2

Why the Switch to Trivalent?

The decision follows recommendations by the World Health Organization (WHO) and the European Medicines Agency (EMA). Both organizations responded to reports and surveillance data showing the B/Yamagata lineage of influenza B has disappeared from circulation worldwide since the COVID-19 pandemic. This historic shift means that the quadrivalent vaccine, which previously included both B/Victoria and B/Yamagata lineages, is being phased out in favor of the trivalent version.who+2

Vaccine Composition for 2025/2026

For the 2025/2026 flu season, Austrian authorities and international regulators recommend:

• A/Victoria/4897/2022 (H1N1)-like virus

• A/Croatia/10136RV/2023 (H3N2)-like virus

• B/Austria/1359417/2021 (B/Victoria lineage)-like virus
  If cell-based vaccines are used, similar recommended strains apply, tailored to the vaccine production platform.cdc+2

Implications and Current Situation

This change is intended to keep vaccination effective and to reflect the present epidemiological reality. The trivalent vaccine protects against the current strains circulating globally, provide coverage for the population, and is recommended for everyone from six months of age and older, especially those at high risk.ema.europa+1

Sources

• European Medicines Agency: EU Recommendations for 2025/2026 seasonal flu vaccine compositionema.europa

• World Health Organization: Recommended composition of influenza virus vaccines for 2025/2026 Northern Hemisphere influenza seasonwho

• CDC: 2025–2026 Flu Season Vaccine Informationcdc