EMA recommends switching from quadrivalent to trivalent flu vaccine this fall

The European Medicines Agency (EMA) has issued influenza virus strain recommendations for vaccine manufacturers to begin switching from quadrivalent to non-B/Yamagata trivalent vaccines for the prevention of seasonal influenza starting in autumn 2024.

Each year, the EMA publishes EU recommendations on the composition of seasonal influenza vaccines, based on observations from the World Health Organization (WHO), which are based on regular activities to monitor the prevalence and characteristics of different influenza viruses around the world.

Currently, most licensed influenza vaccines are quadrivalent, meaning they are designed to protect against the four main influenza strains that cause seasonal influenza: A(H1N1)pdm09 and A(H3N2), B/Victoria and B/Yamagata. However, the BB/Yamagata influenza virus strain has not been detected in circulation since March 2020. This is believed to be partly due to public health measures taken to limit the spread of COVID-19 during the pandemic. Influenza B viruses are responsible for a quarter of annual influenza infections.

Since the B-Yamagata virus strain no longer poses a public health threat, there is no need to include it in influenza vaccines. The ETF recommends that this strain should ideally be excluded from all live attenuated vaccines from the 2024/2025 season. To ensure supply of vaccines for the next vaccination campaign, the transition to the trivalent composition of all other influenza vaccines must be completed by the 2025/2026 season.

Taking into account the ETF’s statement and the WHO’s insights and recommendations, the EMA Influenza Task Force has issued the following strain recommendations for this year.

Manufacturers of live attenuated vaccines or trivalent egg-based vaccines must include in the 2024/2025 season. these three strains of the virus: virus similar to A/Victoria/4897/2022 (H1N1)pdm09; virus similar to A/Thailand/8/2022 (H3N2); virus similar to B/Austria/1359417/2021 (B/Victoria lineage).

Manufacturers of trivalent cell-based vaccines must include these three virus strains in the 2024/2025 season: a virus similar to A/Wisconsin/67/2022 (H1N1)pdm09; virus similar to A/Massachusetts/18/2022 (H3N2); virus similar to B/Austria/1359417/2021 (B/Victoria lineage).

Manufacturers of inactivated vaccines may consider producing a quadrivalent vaccine containing two strains of influenza B virus for the 2024/2025 season. In this case, in addition to the strains mentioned above, a virus similar to B/Phuket/3073/2013 (lineage B/Yamagata) is considered suitable.

Recommendations for the 2024/2025 influenza season. were approved by the EMA Committee for Medicinal Products for Human Use (CHMP) at its meeting in March 2024 and updated at its meeting in May 2024.

Influenza viruses are constantly changing and evolving. Therefore, it is necessary to periodically change the virus strains contained in influenza vaccines to maintain the effectiveness of the vaccines.

The agency encourages marketing authorization holders to submit reformulation applications for centrally authorized seasonal influenza vaccines by June 17, 2024.