The FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) met in early March and made recommendations on the selection of viruses for the composition of influenza vaccines for the 2024–2025 U.S. influenza season.
Last fall, the committee and FDA representatives discussed whether there was a continued need for a quadrivalent formulation of seasonal influenza vaccine for the United States. The issue was the lack of any confirmed detections of circulating B/Yamagata lineage viruses worldwide after March 2020.
Influenza B viruses are classified into two lineages: B/Yamagata and B/Victoria. “However, the evidence indicates that the B/Yamagata lineage virus no longer poses a public health threat,” according to an FDA press release. “During the October 2023 meeting, the committee unanimously voted to recommend excluding the B/Yamagata lineage component from quadrivalent seasonal influenza vaccines as soon as possible.”
The FDA strongly recommended to influenza vaccine manufacturers the removal of the B/Yamagata lineage virus from seasonal influenza vaccines in the U.S. for the 2024–2025 influenza season. The agency said it and vaccine manufacturers have been working together so that the move from quadrivalent to trivalent seasonal influenza vaccines occurs for the upcoming influenza season.
The influenza virus strains for a trivalent vaccine composition for use in the U.S. were recommended early this month based on the influenza vaccine production method: egg-based and cell- or recombinant-based. Trivalent seasonal influenza vaccines now include two influenza A viruses (H1N1 and H3N2) and one influenza B virus.
The committee recommended that the trivalent formulation of egg-based influenza vaccines for the U.S. 2024–2025 influenza season contain the following:
• An A/Victoria/4897/2022 (H1N1)pdm09–like virus
• An A/Thailand/8/2022 (H3N2)–like virus
• A B/Austria/1359417/2021 (B/Victoria lineage)–like virus.
The committee recommended that the trivalent formulation of cell- or recombinant-based influenza vaccines for the U.S. 2024–2025 influenza season contain the following:
• An A/Wisconsin/67/2022 (H1N1)pdm09–like virus
• An A/Massachusetts/18/2022 (H3N2)–like virus
• A B/Austria/1359417/2021 (B/Victoria lineage)–like virus.
“Of note, not all countries will be able to revert to trivalent seasonal influenza vaccines as quickly as FDA has facilitated the process for the United States,” according to the press release. “For those manufacturers who have an existing FDA-approved quadrivalent seasonal influenza vaccine and want to export that quadrivalent vaccine for use outside the United States, the committee also recommended the inclusion of a second B strain, a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus for quadrivalent egg-, cell- or recombinant-based vaccines.”
The FDA officials say they anticipate that there will be an adequate and diverse supply of approved trivalent seasonal influenza vaccines for the U.S. in the coming season.
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