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CompletedNCT05874713Updated Dec 13, 2024

Study to Evaluate Safety and Immunogenicity of Different Priming and Booster Regimens With Adjuvanted H5N8 and/or H5N6 Influenza Vaccine in Adults

A Phase 2 interventional study of aH5N8c on Day 1 and aH5N6c on Day 1 in Influenza, Human, Infections and Respiratory Tract Infections, sponsored by Seqirus. Completed at 9 sites in United States. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2024-12-13.

Sponsored by Seqirus (part of CSL Limited) · Phase 2, Interventional, and Prevention

From the registry’s dates

  • Primary completion was Apr 2024, 2 years 6 months ago, and no results have been posted to the registry; the sponsor requested a delay in submitting them in Dec 2024.
Phase
Phase 2
Study type
Interventional
Enrollment
480
Allocation
Randomized
Ages
18 Years and older
Sex
All
01

Study summary

This Phase 2, randomized, observer-blind clinical study is evaluating 3 different priming and booster regimens with MF59-adjuvanted H5N8 and/or H5N6 cell culture-derived influenza vaccine (aH5N8c; aH5N6c). Approximately 480 healthy adult subjects are to be randomized into 1 of 3 possible treatment groups, stratified by age group (18-64 years and ≥65 years) and by poultry worker status (yes/no). Each subject will receive a priming influenza vaccine injection on Day 1 and Day 22 and a booster vaccination on Day 202. Subjects will be followed up for approximately 6 months after the booster injection.

The primary immunogenicity analysis is based on antibody responses against H5N8 and H5N6 as measured by hemagglutination inhibition (HI) assay on Day 1, Day 22, Day 29, Day 43, Day 202, Day 209 (H5N8 only), and Day 223.

02

Conditions studied

  • Influenza, Human
  • Infections
  • Respiratory Tract Infections
  • Virus Diseases
  • Infection Viral

Keywords

  • Influenza
  • Vaccine
  • MF59
  • Adjuvant
  • H5N8
  • H5N6
  • Pandemic
  • Avian
03

In context

Influenza, Human

2,356 studies on the registry are indexed under Influenza, Human; 184 are open to participants now.

This study's enrollment of 480 is above the median of 227 across 1,957 interventional studies indexed under Influenza, Human.

Browse Influenza, Human studies →

Lead sponsor

Seqirus is the lead sponsor of 53 studies on the registry; none are open to participants now.

Of its 15 completed or terminated interventional studies of FDA-regulated products, 10 (67%) have results posted.

First submitted after Seqirus became part of CSL Limited.

Browse Seqirus studies →All CSL Limited studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
Yes

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • Individuals of ≥18 years of age on the day of .
  • Individuals who or whose legally acceptable representative(s) have voluntarily given written consent after the nature of the study has been explained according to local regulatory requirements, prior to study entry.
  • Individuals who can comply with study procedures including follow-up.
  • Males, females of non- or females of childbearing potential who are using an effective method which they intend to use for at least 30 days before the first study vaccination and plan to do so until 2 months after the last study vaccination.
  • Individuals must provide a baseline blood sample prior to randomization and vaccination.

Exclusion criteria

Exclusion Criteria:

  • Females of who are pregnant, lactating, or who have not adhered to a specified set of methods from at least 30 days prior to study entry and who do not plan to do so until 2 months after the last study vaccination.
  • Progressive, unstable or uncontrolled clinical conditions.
  • , including allergy, to any component of vaccines, medicinal products or medical equipment whose use is foreseen in this study.
  • Clinical conditions representing a to intramuscular vaccination and blood draws.

  • Abnormal function of the immune system resulting from:

    1. Clinical conditions.
    2. Systemic administration of at a dose ≥20 mg/day of prednisone (or equivalent) for more than 14 consecutive days within 90 days prior to . Topical, inhaled and intranasal corticosteroids are permitted. Intermittent use (one dose in 30 days) of intra-articular corticosteroids are also permitted.
    3. Administration of antineoplastic and immunomodulating agents or radiotherapy within 90 days prior to informed consent.
  • History of any medical condition considered an AESI.
  • Received immunoglobulins with immunomodulating effects or any blood products within 180 days prior to informed consent.
  • Individuals who previously received an H5 influenza vaccine or have a known history of H5 influenza infection prior to enrollment.
  • Received an or non-registered medicinal product within 30 days prior to informed consent or are unwilling to refuse participation in another clinical study at any time during the conduct of this study.
  • Study personnel or immediate family or household member of study personnel.
  • Any other clinical condition that, in the opinion of the investigator, might interfere with the results of the study or pose additional risk to the individual due to participation in the study.
  • Individuals who received any other vaccines (with the exception of COVID-19 vaccines) within 14 days (for inactivated vaccines) or 28 days (for ) prior to enrolment in this study or who are planning to receive any vaccine within 28 days from any of the 3 scheduled study vaccinations.
  • Receipt of any (investigational or licensed) COVID-19 vaccine within 14 days (non-replicating vaccines) or 28 days (replicating vaccines) prior to enrollment or plan to receive any COVID-19 vaccine within 7 days from any of the 3 scheduled study vaccinations.
  • A known history of Guillain-Barre Syndrome or other demyelinating diseases such as encephalomyelitis and transverse myelitis.
Terms in these criteria, in plain language(8)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Childbearing potential

Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).

Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Contraindication

A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Live vaccines

Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.

05

Study design

Phase
Phase 2
Primary purpose
Prevention
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Triple (Participant, Investigator, Outcomes assessor)
Enrollment
480 participants (actual)

Study arms

  • Experimental
    Arm A

    Eligible subjects who have been randomized to receive aH5N8c on Day 1, Day 22 and Day 202

    Biological: aH5N8c on Day 1 · Biological: aH5N8c on Day 22 · Biological: aH5N8c on Day 202

  • Experimental
    Arm B

    Eligible subjects who have been randomized to receive aH5N8c on Day 1, aH5N6c on Day 22, and aH5N8c on Day 202

    Biological: aH5N8c on Day 1 · Biological: aH5N6c on Day 22 · Biological: aH5N8c on Day 202

  • Experimental
    Arm C

    Eligible subjects who have been randomized to receive aH5N6c on Day 1 and aH5N8c on Day 22 and Day 202

    Biological: aH5N6c on Day 1 · Biological: aH5N8c on Day 22 · Biological: aH5N8c on Day 202

Interventions

  • BiologicalaH5N8c on Day 1

    MF59-adjuvanted cell-culture derived subunit inactivated monovalent A/H5N8 vaccine (aH5N8c) for intramuscular administration, containing intermediate dose H5N8 hemagglutinin + standard dose MF59 (approximately 0.5 mL total volume)

  • BiologicalaH5N6c on Day 1

    MF59-adjuvanted cell-culture derived subunit inactivated monovalent A/H5N6 vaccine (aH5N6c) for intramuscular administration, containing intermediate dose H5N6 hemagglutinin + standard dose MF59 (approximately 0.5 mL total volume)

  • BiologicalaH5N8c on Day 22

    MF59-adjuvanted cell-culture derived subunit inactivated monovalent A/H5N8 vaccine (aH5N8c) for intramuscular administration, containing intermediate dose H5N8 hemagglutinin + standard dose MF59 (approximately 0.5 mL total volume)

  • BiologicalaH5N6c on Day 22

    MF59-adjuvanted cell-culture derived subunit inactivated monovalent A/H5N6 vaccine (aH5N6c) for intramuscular administration, containing intermediate dose H5N6 hemagglutinin + standard dose MF59 (approximately 0.5 mL total volume)

  • BiologicalaH5N8c on Day 202

    MF59-adjuvanted cell-culture derived subunit inactivated monovalent A/H5N8 vaccine (aH5N8c) for intramuscular administration, containing intermediate dose H5N8 hemagglutinin + standard dose MF59 (approximately 0.5 mL total volume)

06

What researchers measure

Primary outcomes

  1. Geometric mean titer (GMT) of hemagglutination inhibition (HI) antibodies against H5N8 strain - Day 1

    GMT (HI) prevaccination

    Time frame: Day 1

  2. GMT of HI antibodies against H5N8 strain - Day 22

    GMT (HI) 3 weeks post first priming vaccination

    Time frame: Day 22

  3. GMT of HI antibodies against H5N8 strain - Day 43

    GMT (HI) 3 weeks post second priming vaccination

    Time frame: Day 43

  4. GMT of HI antibodies against H5N8 strain - Day 202

    GMT (HI) pre booster vaccination

    Time frame: Day 202

  5. GMT of HI antibodies against H5N8 strain - Day 209

    GMT (HI) 1 week post booster vaccination

    Time frame: Day 209

  6. GMT of HI antibodies against H5N8 strain - Day 223

    GMT (HI) 3 weeks post booster vaccination

    Time frame: Day 223

  7. GMT of HI antibodies against H5N6 strain - Day 1

    GMT (HI) prevaccination

    Time frame: Day 1

  8. GMT of HI antibodies against H5N6 strain - Day 22

    GMT (HI) 3 weeks post first priming vaccination

    Time frame: Day 22

  9. GMT of HI antibodies against H5N6 strain - Day 43

    GMT (HI) 3 weeks post second priming vaccination

    Time frame: Day 43

  10. GMT of HI antibodies against H5N6 strain - Day 202

    GMT (HI) pre booster vaccination

    Time frame: Day 202

  11. GMT of HI antibodies against H5N6 strain - Day 223

    GMT (HI) 3 weeks post booster vaccination

    Time frame: Day 223

  12. Geometric mean fold increase (GMFI) of HI antibodies against H5N8 strain - Day 22

    GMFI (HI) 3 weeks post first priming vaccination compared to prevaccination

    Time frame: Day 22

  13. GMFI of HI antibodies against H5N8 strain - Day 43

    GMFI (HI) 3 weeks post second priming vaccination compared to prevaccination

    Time frame: Day 43

  14. GMFI of HI antibodies against H5N8 strain - Day 209

    GMFI (HI) 1 week post booster vaccination compared to pre booster vaccination

    Time frame: Day 209

  15. GMFI of HI antibodies against H5N8 strain - Day 223

    GMFI (HI) 3 weeks post booster vaccination compared to pre booster vaccination

    Time frame: Day 223

  16. GMFI of HI antibodies against H5N6 strain - Day 22

    GMFI (HI) 3 weeks post first priming vaccination compared to prevaccination

    Time frame: Day 22

  17. GMFI of HI antibodies against H5N6 strain - Day 43

    GMFI (HI) 3 weeks post second priming vaccination compared to prevaccination

    Time frame: Day 43

  18. GMFI of HI antibodies against H5N6 strain - Day 223

    GMFI (HI) 3 weeks post booster vaccination compared to pre booster vaccination

    Time frame: Day 223

  19. Percentages of subjects with HI titers ≥1:40 against H5N8 strain - Day 1

    % ≥1:40 (HI) prevaccination

    Time frame: Day 1

  20. Percentages of subjects with HI titers ≥1:40 against H5N8 strain - Day 22

    % ≥1:40 (HI) 3 weeks post first priming vaccination

    Time frame: Day 22

  21. Percentages of subjects with HI titers ≥1:40 against H5N8 strain - Day 43

    % ≥1:40 (HI) 3 weeks post second priming vaccination

    Time frame: Day 43

  22. Percentages of subjects with HI titers ≥1:40 against H5N8 strain - Day 209

    % ≥1:40 (HI) 1 week post booster vaccination

    Time frame: Day 209

  23. Percentages of subjects with HI titers ≥1:40 against H5N8 strain - Day 223

    % ≥1:40 (HI) 3 weeks post booster vaccination

    Time frame: Day 223

  24. Percentages of subjects with HI titers ≥1:40 against H5N6 strain - Day 1

    % ≥1:40 (HI) prevaccination

    Time frame: Day 1

  25. Percentages of subjects with HI titers ≥1:40 against H5N6 strain - Day 22

    % ≥1:40 (HI) 3 weeks post first priming vaccination

    Time frame: Day 22

  26. Percentages of subjects with HI titers ≥1:40 against H5N6 strain - Day 43

    % ≥1:40 (HI) 3 weeks post second priming vaccination

    Time frame: Day 43

  27. Percentages of subjects with HI titers ≥1:40 against H5N6 strain - Day 223

    % ≥1:40 (HI) 3 weeks post booster vaccination

    Time frame: Day 223

  28. Percentages of subjects with seroconversion by HI against H5N8 strain - Day 22

    % seroconversion (HI) 3 weeks post first priming vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with prevaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 22

  29. Percentages of subjects with seroconversion by HI against H5N8 strain - Day 43

    % seroconversion (HI) 3 weeks post second priming vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with pre-vaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 43

  30. Percentages of subjects with seroconversion by HI against H5N8 strain - Day 209

    % seroconversion (HI) 1 week post booster vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with pre-vaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 209

  31. Percentages of subjects with seroconversion by HI against H5N8 strain - Day 223

    % seroconversion (HI) 3 weeks post booster vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with pre-vaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 223

  32. Percentages of subjects with seroconversion by HI against H5N6 strain - Day 22

    % seroconversion (HI) 3 weeks post first priming vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with pre-vaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 22

  33. Percentages of subjects with seroconversion by HI against H5N6 strain - Day 43

    % seroconversion (HI) 3 weeks post second priming vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with pre-vaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 43

  34. Percentages of subjects with seroconversion by HI against H5N6 strain - Day 223

    % seroconversion (HI) 3 weeks post booster vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with pre-vaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 223

Secondary outcomes

  1. Frequency and severity of solicited local and systemic adverse events (AEs)

    For 7 consecutive days following each vaccination (ie, Day 1 through Day 7, Day 22 through Day 28, and Day 202 through 208, or until symptom resolution if ongoing at Day 7, Day 28 or Day 208 for a maximum of 14 days postvaccination).

    Time frame: Day 1 through Day 7, Day 22 through Day 28, and Day 202 through 208

  2. Frequency and severity of unsolicited AEs

    For 3 weeks following each vaccination

    Time frame: Day 1 through Day 43 and Day 202 through Day 223

  3. Frequency and severity of serious AEs (SAEs), AEs leading to withdrawal, AEs of special interest (AESI), and medically attended AEs (MAAEs)

    From first vaccination until study completion

    Time frame: Day 1 through Day 382

  4. GMT of HI antibodies against H5N8 strain - Persistence

    GMT (HI) 6 months post 2nd priming vaccination and 6 months post booster vaccination

    Time frame: Day 202, Day 382

  5. GMT of HI antibodies against H5N6 strain - Persistence

    GMT (HI) 6 months post 2nd priming vaccination

    Time frame: Day 202

  6. GMFI of HI antibodies against H5N8 strain - Persistence

    GMFI (HI) 6 months post 2nd priming vaccination compared to prevaccination (Day 1), and 6 months post booster vaccination compared to prevaccination (Day 1) and compared to pre booster vaccination (Day 202)

    Time frame: Day 202, Day 382

  7. GMFI of HI antibodies against H5N6 strain - Persistence

    GMFI (HI) 6 months post 2nd priming vaccination compared to prevaccination

    Time frame: Day 202

  8. Percentages of subjects with HI titers ≥1:40 against H5N8 strain - Persistence

    % ≥1:40 (HI) 6 months post 2nd priming vaccination and 6 months post booster vaccination

    Time frame: Day 202, Day 382

  9. Percentages of subjects with HI titers ≥1:40 against H5N6 strain - Persistence

    % ≥1:40 (HI) 6 months post 2nd priming vaccination

    Time frame: Day 202

  10. Percentages of subjects with seroconversion by HI against H5N8 strain - Persistence

    % seroconversion (HI) 6 months post 2nd priming vaccination and 6 months post booster vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with pre-vaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 202, Day 382

  11. Percentages of subjects with seroconversion by HI against H5N6 strain - Persistence

    % seroconversion (HI) 6 months post 2nd priming vaccination, defined as a ≥4-fold increase in HI titer postvaccination in those with pre-vaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with prevaccination titer \<1:10

    Time frame: Day 202

  12. GMT of microneutralization (MN) antibodies against H5N8 strain

    GMT (MN) prevaccination, 3 weeks post priming vaccinations, pre booster vaccination and 3 weeks post booster vaccination

    Time frame: Day 1, Day 22, Day 43, Day 202, Day 223

  13. GMT of MN antibodies against H5N6 strain

    GMT (MN) prevaccination, 3 weeks post 2nd priming vaccination, pre booster vaccination and 3 weeks post booster vaccination

    Time frame: Day 1, Day 43, Day 202, Day 223

  14. GMFI of MN antibodies against H5N8 strain

    GMFI (MN) 3 weeks post priming vaccinations and 6 months post 2nd priming vaccination compared to prevaccination (Day 1), and 3 weeks post booster vaccination compared to pre booster vaccination (Day 202)

    Time frame: Day 22, Day 43, Day 202, Day 223

  15. GMFI of MN antibodies against H5N6 strain

    GMFI (MN) 3 weeks and 6 months post 2nd priming vaccination compared to prevaccination (Day 1), and 3 weeks post booster vaccination compared to pre booster vaccination (Day 202)

    Time frame: Day 43, Day 202, Day 223

  16. Percentages of subjects with MN titers ≥1:40 against H5N8 strain

    % ≥1:40 (MN) prevaccination, 3 weeks post priming vaccinations, pre booster vaccination, and 3 weeks post booster vaccination

    Time frame: Day 1, Day 22, Day 43, Day 202, Day 223

  17. Percentages of subjects with MN titers ≥1:40 against H5N6 strain

    % ≥1:40 (MN) prevaccination, 3 weeks post 2nd priming vaccination, pre booster vaccination, and 3 weeks post booster vaccination

    Time frame: Day 1, Day 43, Day 202, Day 223

  18. Percentages of subjects with seroconversion by MN against H5N8 strain

    % seroconversion (MN) 3 weeks post priming vaccinations, pre booster vaccination, and 3 weeks post booster vaccination, defined as a ≥4-fold increase in MN titer postvaccination for subjects with prevaccination titer ≥lower limit of quantification (LLOQ), or a postvaccination MN titer ≥4×LLOQ for subjects with prevaccination titer \<LLOQ

    Time frame: Day 22, Day 43, Day 202, Day 209, Day 223

  19. Percentages of subjects with seroconversion by MN against H5N6 strain

    % seroconversion (MN) 3 weeks post 2nd priming vaccination, pre booster vaccination, and 3 weeks post booster vaccination, defined as a ≥4-fold increase in MN titer postvaccination for subjects with prevaccination titer ≥lower limit of quantification (LLOQ), or a postvaccination MN titer ≥4×LLOQ for subjects with prevaccination titer \<LLOQ

    Time frame: Day 43, Day 202, Day 209, Day 223

07

Study locations

9 sites
  • Cullman Clinical Trials
    Cullman, Alabama 35055, United States
  • Lifeline Primary Care
    Lilburn, Georgia 30047, United States
  • Georgia Clinic
    Norcross, Georgia 30092, United States
  • Velocity Clinical Research
    Sioux City, Iowa 51106, United States
  • Velocity Clinical Research
    Baton Rouge, Louisiana 70809, United States
  • Velocity Clinical Research
    Grand Island, Nebraska 68803, United States
  • Velocity Clinical Research
    Norfolk, Nebraska 68701, United States
  • Medical Care LLC
    Elizabethton, Tennessee 37643, United States
  • Cope Family Medicine
    Bountiful, Utah 84010, United States
08

References and documents

Individual participant data

Plan to share: Undecided

No publications or documents are linked to this record.

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Dec 13, 2024, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT05874713
Lead sponsor
Seqirus
Collaborators
Biomedical Advanced Research and Development Authority
Responsible party
Sponsor
First posted
May 25, 2023
Start date
Jun 7, 2023
Primary completion
Apr 25, 2024
Completion
Sep 25, 2024
Last update
Dec 13, 2024

Study contacts

Therapeutic Area Head
study chair · Seqirus

Oversight

Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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