Influenza B Strain Removal Could Impact Future Flu Vaccines

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WHO and VRBPAC recommendations to move back toward trivalent influenza vaccines may cause significant shifts in the global flu vaccine landscape.

On Thursday, October 5, 2023, the Food and Drug Administration (FDA) Vaccines and Related Biologic Products Advisory Committee (VRBPAC) voted unanimously to recommend the removal of one influenza B virus component currently included in quadrivalent influenza vaccines (QIV) “as soon as possible.” The panel’s action follows the World Health Organization’s (WHO) recommendations, pointing to the potential for a significant shift in the global influenza vaccine landscape in the coming months.

Implications of VRBPAC’s Recommendation

The October 5 meeting occurred as part of the regular lifecycle of decisions and recommendations on strain composition. WHO coordinates year-round global surveillance through its network of national influenza centers and regional collaborating centers. Twice a year, it convenes collaborating center leaders to review data generated via the global surveillance network to issue recommendations for the virus components for the northern hemisphere and southern hemisphere. It is then up to national regulators—such as the FDA in the US—to decide whether to adopt those recommendations. The FDA’s VRBPAC convenes biannually in March and October to select viruses for seasonal influenza vaccine composition.

Until 2012, influenza vaccines were all trivalent. The quadrivalent product was first introduced in response to two distinct influenza B virus lineages circulating. Only for the 2021–2022 season did the US market shift entirely to QIV.

During last week’s meeting, the expert panel met to consider WHO’s late September recommendation for the southern hemisphere influenza vaccine strain composition for the 2024 season. It endorsed WHO recommendations on components for the southern hemisphere trivalent influenza vaccine (TIV) and QIV. VRBPAC members and representatives from industry, government, and the WHO acknowledged that a complete switch to TIV is not practical for the southern hemisphere season. It also reaffirmed the WHO strain selection advisory committee’s recommendation that manufacturers and national regulators begin removing the B/Yamagata lineage component of influenza vaccines, which has gone undetected by WHO’s network of surveillance centers since 2020. WHO collaborating center leaders and VRBPAC advisors agreed that this points to a low threat of infection from that virus and to its possible extinction.

VRBPAC signaled to regulators and stakeholders its intention to change composition recommendations for the northern hemisphere vaccine for the 2024–2025 season as well. The vote to select and recommend those strains will occur in spring 2024 and would likely feature consideration of a move either toward all TIV or TIV/QIV in the US. VRBPAC and other national regulators often follow the strain selection recommendations issued by WHO, which likely indicates that similar TIV recommendations will be adopted by regulatory authorities in other key markets.

Policy Considerations

As this matter continues to unfold for the upcoming 2024–2025 influenza vaccine season, unanswered issues remain that will be determined over time.

  1. Additional clarity from FDA on product-specific regulatory pathways toward TIV or alternate QIV: Product-specific detail on licensure requirements for TIV is needed. The agency may take a different approach to QIV composition in the future (i.e., the addition of an additional influenza A or different B lineage virus component), but changes would require more guidance on licensure requirements and additional data.
  2. Vaccine manufacturing and supply: FDA advisors asked for more detail around the potential for disruption in supply for the 2024–2025 season should TIV vaccines be recommended. They also renewed calls for more modernized, more nimble influenza vaccine production processes.
  3. Forecasting around the future of influenza B viruses: A recommendation to return to TIV underscores the unpredictable nature of influenza vaccine manufacturing and the critical value of better influenza virologic forecasting data.
  4. Pricing: Influenza vaccine pricing has been responsive to changes in the composition of vaccines. Reintroduction of TIV vaccines into the US market signals the potential for differential pricing for TIV and QIV products. Avalere can help manufacturers navigate the access and payer landscape associated with this new market dynamic.

Navigating the Evolving Influenza Vaccine Landscape

Avalere’s experts in vaccine policy and commercial strategy can help manufacturers and other stakeholders analyze the policy and access implications of the shift to trivalent influenza vaccines and help companies develop strategies to differentiate their platforms in the evolving landscape. To learn how Avalere can support you with analysis, strategy development, and stakeholder engagement, connect with us.

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