Data published in The Lancet Infectious Diseases reveals that a 7,699-person Phase 3 study of CSL Seqirus’s MF59-adjuvanted, cell-based, higher-dose quadrivalent vaccine (aQIVc) demonstrated superior immunogenicity against all four influenza strains compared to an adjuvanted egg-based comparator, according to recent findings. The study also showed non-inferiority against a recombinant vaccine for three of four strains in adults aged 50 and older, and for all four strains in individuals 65 and older.
Combining Three Enhancement Strategies for Older Adults
While researchers have long utilized individual enhancement technologies, stacking three distinct strategies into a single shot had not previously been evaluated in a large-scale trial, according to data from The Lancet Infectious Diseases. Cell-based manufacturing has been deployed since the 2012 approval of Flucelvax to improve strain matching. Meanwhile, the MF59 adjuvant maintains an established track record in older demographics, and higher antigen doses have remained available since the 2009 licensing of Sanofi’s Fluzone High-Dose.
The new Phase 3 trial establishes that combining all three components in one formulation produces sustained immune responses through the full influenza season. Most adverse reactions reported in the study were mild to moderate, resolving within three days. This persistence is particularly critical for older adults, as immune senescence naturally blunts and shortens vaccine-induced protection.
Exploratory Neuraminidase Findings and Regulatory Status
Beyond standard immunogenicity endpoints, the trial reported exploratory data regarding neuraminidase antibody responses. According to the study authors, neuraminidase antibody levels were higher for aQIVc than for both comparator vaccines. Because neuraminidase immunity is not yet classified as a regulatory endpoint, the researchers frame the metric as requiring further evaluation rather than acting as a proven efficacy signal.
Despite this, the finding provides immunization advisory groups with an additional variable to weigh when comparing enhanced vaccine options for older populations. AUJEMFLU, the marketed name for the trivalent formulation of aQIVc, has already secured approval from the MHRA for adults 50 and older in the UK and received authorization from the European Commission.
Future Rollout and Advisory Timelines
CSL Seqirus has filed regulatory applications in additional markets and intends to execute a phased rollout tied to local regulatory and policy timelines. According to industry tracking, the immediate indicator to watch is whether National Immunisation Technical Advisory Groups in pending markets incorporate the Lancet data when establishing enhanced-vaccine recommendations for the 2027 season.
Did You Know? Immune senescence is a natural biological process that gradually degrades the immune system’s ability to respond effectively to new infections and standard-dose vaccinations over time.
Frequently Asked Questions
What did the Lancet Infectious Diseases study evaluate?
The Phase 3 study evaluated a 7,699-person trial testing CSL Seqirus’s aQIVc vaccine, which combines an MF59 adjuvant, cell-based manufacturing, and a higher antigen dose into a single quadrivalent shot.
How did aQIVc perform compared to existing comparators?
According to published data, aQIVc demonstrated superior immunogenicity against all four influenza strains compared to an adjuvanted egg-based comparator. It also showed non-inferiority against a recombinant vaccine for three of four strains in adults 50 and older, and all four strains in those 65 and older.
Where is the vaccine currently approved?
The trivalent formulation of aQIVc, marketed as AUJEMFLU, has cleared the MHRA for adults 50 and older in the UK and received approval from the European Commission, with filings pending in additional markets.
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