CSL Seqirus confirmed it is fully prepared to deliver its influenza vaccine portfolio for the 2024/25 U.S. season, based on the trivalent strains recommended this week by the U.S. Food and Drug Administration's (FDA) Vaccines and Related Biological Products Advisory Committee (VRBPAC). During the meeting, the committee confirmed the viral strain selection of influenza vaccines for the Northern Hemisphere 2024/25 season, which aligns with the February 2024World Health Organization (WHO) annual recommendations and is unchanged from the Southern Hemisphere 2024 season. The VRBPAC's recommendation follows the October 2023 VRBPAC meeting, where the committee strongly supported the WHO's recommendation to expeditiously remove the B/Yamagata influenza virus strain from quadrivalent influenza vaccines and transition to trivalent influenza vaccines for the 2024/25 season.

The recommendation was grounded in data from the WHO's global influenza response and surveillance system, which detected a decline in B/Yamagata circulation before the onset of the COVID-19 pandemic and no further circulation of B/Yamagata lineage viruses since March of 2020. The strain selection for the 2024/25 influenza season reflects the removal of B/YamagATA and it will not be included in the vaccines manufactured and delivered by CSL Seqirus. CSL Seqirus worked closely with the FDA during 2023 to align on a path forward and is fully prepared to transition its complete portfolio of seasonal influenza vaccines in the U.S. market from quadrivalent to trivalent formulations for the 2024/25 influenza year.

CSL Seqirus completed its transition plan for the 2024/2025 season by December 2023 and regulatory and manufacturing teams are on track to convert the full U.S. portfolio. As a result of this effort, CSL Seqirus received FDA approval on March 4, 2024 for all of its U.S. trivalent influenza vaccines. Across the world, CSL Seqirus is collaborating with regulatory bodies and public health authorities on an appropriate transition timeline for each country that aims to ensure a smooth transition, increase vaccine confidence and improve immunization rates.

The undetectable circulation of B/YamAGata is a testament to the critical role of widely implemented influenza immunization programs, amongst other contributing factors such as the inherent characteristics and epidemiology of the B/YamagATA virus and the unique environment created by the COVID-19 pand pandemic.