CSL Seqirus, a business of CSL announced publication of pivotal Phase 3 study results for its MF59®-adjuvanted cell-based higher-dose quadrivalent influenza vaccine (aQIVc) in The Lancet Infectious Diseases, marking an important milestone in the evolution of influenza prevention for older adults.

The publication follows approval of the trivalent formulation of aQIVc by the Medicines and Healthcare products Regulatory Agency (MHRA) in the United Kingdom earlier this year for adults aged 50 years and older.2 The vaccine, marketed as AUJEMFLU®, has also been approved by the European Commission for adults aged 50 years and above.

The peer-reviewed publication reports findings from a large-scale study of the first influenza vaccine to combine three proven approaches to enhancing protection in older adults: MF59® adjuvant, cell-based manufacturing, and a higher dose formulation compared to standard influenza vaccines.1,3

Each of these approaches has been used separately in influenza vaccines for many years and is supported by extensive clinical and real-world evidence. This publication provides the first large-scale evaluation of their combination within a single vaccine.

Influenza remains a significant public health challenge, causing substantial illness, hospitalisations and deaths each year despite widespread vaccination programmes.4 

Older adults are particularly vulnerable because the immune system becomes less responsive with age, reducing its ability to mount a strong protective response following vaccination.5 

aQIVc combines three proven approaches to enhancing vaccine protection in older adults, with each playing a distinct and complementary role. Cell-based manufacturing helps preserve a closer match to circulating influenza strains, MF59® adjuvant strengthens, broadens and lengthens the immune response and a higher dose formulation further optimises that response.2,6,7,8

The Phase 3 randomised immunogenicity and safety study enrolled 7,699 adults aged 50 years and older across eight countries and compared aQIVc with two enhanced influenza vaccines. The study met its primary objectives and demonstrated:1

  • Superiority versus the adjuvanted egg-based influenza vaccine comparator across all four influenza strains and age groups assessed.
  • Non-inferiority versus a recombinant influenza vaccine for three out of four strains in the 50+ age group and four out of four strains in those aged 65+.
  • Immune responses that persisted throughout the influenza season.
  • A well-tolerated safety profile. Most reactions were mild or moderate and resolved within three days.1  

The publication also reported exploratory findings of enhanced neuraminidase antibody responses versus comparators. The role of neuraminidase antibodies is an emerging area of influenza research that may contribute to reduced disease severity and broader protection beyond traditional measures of vaccine response.

The study authors concluded that the findings support further evaluation of the vaccine and provide evidence for National Immunisation Technical Advisory Groups considering enhanced influenza vaccination strategies for older adults.1

Regulatory submissions for the trivalent formulation of aQIVc have been made in multiple markets, with introductions expected to occur through a phased approach aligned to local regulatory, policy and access pathways.