A Phase 3 interventional study of Investigational aQIVc and licensed QIVr in Influenza, Human, sponsored by Seqirus. Completed at 96 sites in 8 countries. Open to participants aged 50 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-04-27.
Sponsored by Seqirus · Phase 3, Interventional, and Prevention
This is a Phase 3, randomized, parallel-group, comparator-controlled, observer-blind, multicenter study of immunogenicity and safety in approximately 7700 male and female adults aged 50 years and older (approximately equally split between two age groups: 50-64 years; 65 years and older), who are healthy or have stable comorbidities that increase their risk of complications from influenza infection. Three lots of aQIVc will be evaluated for consistency and pooled for the comparison with the 2 control vaccines.
Subjects will be randomly assigned to receive 1 of 3 lots of aQIVc, QIVr, or aQIV in a 1:1:1:2:2 ratio (for a 3:2:2 ratio for aQIVc, QIVr, and aQIV).
The study will have a treatment period (Day 1 to Day 29) and a follow-up period (Day 30 up to Day 181); a subset of 770 subjects will be followed up up to Day 365.
Main Inclusion Criteria:
Main Exclusion Criteria:
Biological: Investigational aQIVc
Biological: licensed QIVr
Biological: licensed aQIV
Investigational Adjuvanted Cell-derived Quadrivalent Influenza vaccine, containing four influenza virus strains (A/H1N1, A/H3N2, B/Yamagata and Victoria lineage) recommended by the WHO (World Health Organization) for quadrivalent vaccines for the respective season.
Recombinant Quadrivalent Influenza Vaccine (Flublok Quadrivalent/Supemtek) containing four influenza virus strains (A/H1N1, A/H3N2, B/Yamagata and Victoria lineage) recommended by the WHO for quadrivalent vaccines for the respective season.
Adjuvanted, egg-derived Quadrivalent Influenza Vaccine (Fluad) containing four influenza virus strains (A/H1N1, A/H3N2, B/Yamagata and Victoria lineage) recommended by the WHO for quadrivalent vaccines for the respective season.
Immunogenicity Endpoint: Humoral immune responses of 3 lots of aQIVc compared in pairs in terms of Day 29 GMT ratio between each pair among the 3 lots, from antibody titers measured via HI assay.
HI assay will be measured using cell-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains.
Time frame: Day 29
Immunogenicity Endpoint: Humoral immune responses of aQIVc in comparison with QIVr and aQIV vaccines in terms of Day 29 GMT and GMT ratio of antibodies measured via HI assay.
HI assay will be measured using cell-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains. Noninferiority of aQIVc versus comparator (QIVr or aQIV) will be demonstrated if the lower limit (LL) of the 2-sided 97.5% CI for the Day 29 GMT ratio (aQIVc/comparator) is ≥0.67 for each of the 4 vaccine strains.
Time frame: Day 29
Immunogenicity Endpoint: Humoral immune responses of aQIVc in comparison with QIVr and aQIV vaccines in terms of Day 1 to Day 29 SCR and SCR difference, from antibody titers measured via HI assay.
HI assay will be measured using cell-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains. SCR is the percentage of subjects with seroconversion (defined as either a prevaccination \[Day 1\] titer \<1:10 and a postvaccination \[Day 29\] titer ≥1:40, or a prevaccination titer ≥1:10 and a ≥4-fold increase in postvaccination titer). Noninferiority of aQIVc versus comparator (QIVr or aQIV) will be demonstrated if the lower limit (LL) of the 2-sided 97.5% CI for the difference in SCR (aQIVc minus comparator) is ≥-10% for each of the 4 vaccine strains.
Time frame: Day 1 and Day 29
Immunogenicity Endpoint: Humoral immune responses of aQIVc in comparison with aQIV vaccine in terms of Day 29 SCR and SCR difference, GMT and GMT ratio of antibodies measured via HI assay in subjects 65 years and older.
HI assay will be measured using cell-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains. Noninferiority will be demonstrated if the LL of the 2-sided adjusted CI for the Day 29 GMT ratio (aQIVc/comparator) is ≥0.67 for each of the 4 vaccine strains, and the LL of the 2-sided adjusted CI for the difference in SCR (aQIVc minus comparator) is ≥-10% for each of the 4 vaccine strains.
Time frame: Day 1 and Day 29
Immunogenicity Endpoint: Humoral immune responses of aQIVc in comparison with QIVr and aQIV vaccines in terms of Day 29 GMT and GMT ratio of antibodies measured via HI assay.
HI assay will be measured using cell-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains. Superiority of aQIVc versus comparator (QIVr and aQIV) will be demonstrated if the LL of the 2-sided 97.5% CI for the inter-group GMT ratio (aQIVc/comparator) is \>1.0 for each of the 4 vaccine strains.
Time frame: Day 29
Immunogenicity Endpoints: For aQIVc, QIVr, and aQIV vaccines, Day 29 GMT, Day 1 to Day 29 GMFI, Percentage of subjects with HI titer ≥1:40 at Day 29, Day 1 to Day 29 SCR, SCR differences and GMT ratio of antibodies measured via HI assay.
HI assay will be measured using cell-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains, overall and by age subgroup.
Time frame: Day 1 and Day 29
Immunogenicity Endpoints: For aQIVc and aQIV vaccines, Day 29 GMT, Day 1 to Day 29 GMFI, Percentage of subjects with HI titer ≥1:40 at Day 29, Day 1 to Day 29 SCR, SCR differences, and GMT ratio of antibodies measured via HI assay.
HI assay will be measured using egg-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains in the HI-egg subset of 2750 subjects, overall and by age subgroup.
Time frame: Day 1 and Day 29
Immunogenicity Endpoints: For aQIVc, QIVr and aQIV vaccines, GMT, GMFI, Percentage of subjects with HI titer ≥1:40, SCR, SCR differences, and GMT ratio of antibodies measured via HI assay.
HI assay will be measured using cell-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains in the long-term subset of 770 subjects, overall and by age subgroup.
Time frame: Day 1 up to Day 365
Immunogenicity Endpoints: For aQIVc, QIVr and aQIV vaccines, GMT, GMFI, SCR, SCR difference, and GMT ratio of antibodies measured via MN assay.
MN assay will be measured using cell-derived target viruses for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria vaccine strains in the long-term subset of 770 subjects, overall and by age subgroup.
Time frame: Day 1 up to Day 365
Safety endpoints: For aQIVc, QIVr and aQIV vaccines, the percentages of Subjects with Solicited Local Adverse Events, Solicited Systemic Adverse Events, and Severe Solicited Local and/or Systemic AEs.
Time frame: Day 1 to Day 7
Safety endpoints: For aQIVc, QIVr and aQIV vaccines, the percentage of Subjects with Unsolicited Adverse Events.
Time frame: Day 1 to Day 29
Safety endpoints: For aQIVc, QIVr and aQIV vaccines, the percentages of subjects with Serious Adverse Events (SAEs), AEs Leading to Withdrawal, Adverse Events of Special Interest (AESI) and non-serious Medically Attended Adverse Events (MAAEs).
Time frame: Day 1 to Day 181
Safety endpoints: For aQIVc, QIVr and aQIV vaccines, the percentages of subjects with Serious Adverse Events (SAEs), AEs Leading to Withdrawal, Adverse Events of Special Interest (AESI) and non-serious Medically Attended Adverse Events (MAAEs).
Long-term safety for the long-term subset of 770 subjects
Time frame: Day 1 to Day 365
Plan to share: Yes — SEQIRUS supports the release of anonymized subject-level and study-level data in compliance with regulatory requirements, including Clinical Documents which are part of the Common Technical Document (CTD) modules submitted to regulatory agencies for public release. Summary results disclosure is either in document form (e.g., International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) E3 Clinical Study Report synopsis) or structured data form (such as summary results in ClinicalTrials.gov (United States) or eudract.ema.europa.eu (EU Clinical Trial Registry \[EU CTR\])).
Supporting information: Study protocol, Sap
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