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Completed

NCT Number: NCT05422326

A Study to Evaluate Safety and Immunogenicity of One or Two Booster Vaccinations With H5N6 Influenza Vaccine in Adults Primed With H5N1 Influenza Vaccine or Unprimed

This is a Phase 2, randomized, multi-center study in approximately 300 adults who received 2 doses of aH5N1c or placebo in and completed the parent study V89_18 in the <65 years of age cohort. The study investigates whether two priming doses of MF59-adjuvanted H5N1 cell culture-derived vaccine (aH5N1c) followed by one or two booster vaccinations with a MF59-adjuvanted H5N6 cell culture derived vaccine (aH5N6c) 3 weeks apart elicit immune responses to the antigens used for priming (H5N1) and boosting (H5N6) after first and second heterologous booster vaccination.

Eligible subjects, who received 2 doses of aH5N1c in the parent study V89_18 are randomized in a 1:1 ratio to receive either two aH5N6c vaccinations, 3 weeks apart (group 1) or an aH5N6c vaccination on Day 1 and saline placebo on Day 22 (group 2). Eligible subjects, who received placebo in the parent study will receive two aH5N6c vaccinations, 3 weeks apart (group 3). After the second vaccine administration, subjects are monitored for approximately 6 months for safety and antibody persistence. The total study duration will be approximately 7 months per subject.

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Key information

Conditions

Influenza, Human Animal Diseases Bird Diseases Infections Influenza in Birds Orthomyxoviridae Infections RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

Optimal Research, LLC, Huntsville, Alabama, United States

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Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Subjects who received 2 doses of aH5N1c vaccine or placebo in and completed the parent study V89_18 in the <65 years of age cohort.
  • Individuals who can comply with study procedures including follow-up.

Exclusion criteria

  • Females of childbearing potential who are pregnant, lactating, or who have not adhered to a specified set of contraceptive methods from at least 30 days prior to study entry and who do not plan to do so until at least 30 days after the last study vaccination.
  • Progressive, unstable or uncontrolled clinical conditions.
  • Hypersensitivity, including allergy, to any component of vaccines, medicinal products or medical equipment whose use is foreseen in this study.
  • Clinical conditions representing a contraindication to intramuscular vaccination and blood draws.
  • Abnormal function of the immune system.
  • History of any medical condition considered an adverse event of special interest (AESI).
  • Received immunoglobulins with immunomodulating effects or any blood products within 180 days prior to informed consent.
  • Subjects, who received an influenza H5 vaccine other than in the V89_18 parent study or have a history of H5 influenza infection prior to enrollment.
  • Received an investigational or non-registered medicinal product within 30 days prior to informed consent.
  • Individuals who received any other vaccines [except corona virus disease 2019 (COVID-19) vaccines] within 14 days (for inactivated vaccines) or 28 days (for live vaccines) prior to enrollment in this study or who are planning to receive any vaccine within 28 days from the study vaccination.
  • Receipt of any COVID-19 vaccine within 7 days prior to enrollment or plan to receive any COVID-19 vaccine within 7 days from study vaccination.
  • Acute (severe) febrile illness.
  • A known history of Guillain-Barre Syndrome or other demyelinating diseases such as encephalomyelitis and transverse myelitis.

Treatment and study plan

aH5N6c on Day 1

Biological

MF59-adjuvanted cell-culture derived subunit inactivated monovalent A/H5N6 vaccine (aH5N6c) for intramuscular (IM) administration, containing 7.5 μg H5N6 hemagglutinin (HA) (A/Guangdong/18SF020/2018 (H5N6)-like) + 0.25 mL MF59 (approximately 0.5 mL total volume)

aH5N6c on Day 22

Biological

MF59-adjuvanted cell-culture derived subunit inactivated monovalent A/H5N6 vaccine (aH5N6c) for intramuscular (IM) administration, containing 7.5 μg H5N6 HA (A/Guangdong/18SF020/2018 (H5N6)-like) + 0.25 mL MF59 (approximately 0.5 mL total volume) given 3 weeks after the first aH5N6c vaccination

Placebo on Day 22

Biological

Saline placebo (sterile, 0.5 mL) given 3 weeks after the aH5N6c vaccination

Primary outcomes

  1. Geometric Mean Titer (GMT) of Hemagglutination Inhibition (HI) Antibodies Against the H5N6 Strain

    Time frame: Day 1, Day 8, Day 22, Day 43

    GMT pre-vaccination, 1 and 3 weeks post-vaccination 1, and 3 weeks post-vaccination 2

    Note: The Overall Number of Participants Analyzed (N) represents the total number of participants in the per-protocol set (PPS); definitions are provided in the Statistical Analysis Plan (SAP). The Number Analyzed (n) at each timepoint corresponds to the number of participants with an available serum analysis result for the relevant strain at that timepoint. Instances where n<N reflect missing serum samples or non-evaluable results. All participants included in the Overall Number of Participants Analyzed contributed data to the analysis at one or more timepoints.

  2. Geometric Mean Fold Increase (GMFI) of HI Antibodies Against the H5N6 Strain

    Time frame: Day 1, Day 8, Day 22, Day 43

    GMFI 1 and 3 weeks post-vaccination 1, and 3 weeks post-vaccination 2 compared to pre-vaccination (Day 1)

    Note: The Overall Number of Participants Analyzed (N) represents the total number of participants in the PPS; definitions are provided in the SAP. The Number Analyzed (n) at each timepoint corresponds to the number of participants with an available serum analysis result for the relevant strain at that timepoint. Instances where n<N reflect missing serum samples or non-evaluable results. All participants included in the Overall Number of Participants Analyzed contributed data to the analysis at one or more timepoints.

  3. Percentage of Subjects With HI Titers ≥1:40 Against the H5N6 Strain

    Time frame: Day 1, Day 8, Day 22, Day 43

    Pre-vaccination, 1 and 3 weeks post-vaccination 1, and 3 weeks post-vaccination 2

    Note: The Overall Number of Participants Analyzed (N) represents the total number of participants in the PPS; definitions are provided in the SAP. The Number Analyzed (n) at each timepoint corresponds to the number of participants with an available serum analysis result for the relevant strain at that timepoint. Instances where n<N reflect missing serum samples or non-evaluable results. All participants included in the Overall Number of Participants Analyzed contributed data to the analysis at one or more timepoints.

  4. Percentage of Subjects With Seroconversion Against the H5N6 Strain

    Time frame: Day 8, Day 22, Day 43

    Seroconversion 1 and 3 weeks post-vaccination 1, and 3 weeks post-vaccination 2, defined as a ≥4-fold increase in HI titer post-vaccination in those with pre-vaccination titer ≥1:10, or a post-vaccination HI titer ≥1:40 for subjects with baseline titer <1:10

    Note: The Overall Number of Participants Analyzed (N) represents the total number of participants in the PPS; definitions are provided in the SAP. The Number Analyzed (n) at each timepoint corresponds to the number of participants with an available serum analysis result for the relevant strain at that timepoint. Instances where n<N reflect missing serum samples or non-evaluable results. All participants included in the Overall Number of Participants Analyzed contributed data to the analysis at one or more timepoints.

Secondary outcomes

  1. GMT of HI Antibodies Against the H5N1 Strain

    Time frame: Day 1, Day 8, Day 22, Day 43, Day 202

    GMT pre-vaccination, 1 and 3 weeks post-vaccination 1, and 3 weeks and 6 months post-vaccination 2

    Note: The Overall Number of Participants Analyzed (N) represents the total number of participants in the PPS; definitions are provided in the SAP. The Number Analyzed (n) at each timepoint corresponds to the number of participants with an available serum analysis result for the relevant strain at that timepoint. Instances where n<N reflect missing serum samples or non-evaluable results. All participants included in the Overall Number of Participants Analyzed contributed data to the analysis at one or more timepoints.

  2. GMFI of HI Antibodies Against the H5N1 Strain

    Time frame: Day 1, Day 8, Day 22, Day 43, Day 202

    GMFI 1 and 3 weeks post-vaccination 1, and 3 weeks and 6 months post-vaccination 2 compared to pre-vaccination (Day 1)

    Note: The Overall Number of Participants Analyzed (N) represents the total number of participants in the PPS; definitions are provided in the SAP. The Number Analyzed (n) at each timepoint corresponds to the number of participants with an available serum analysis result for the relevant strain at that timepoint. Instances where n<N reflect missing serum samples or non-evaluable results. All participants included in the Overall Number of Participants Analyzed contributed data to the analysis at one or more timepoints.

  3. Percentage of Subjects With HI Titers ≥1:40 Against the H5N1 Strain

    Time frame: Day 1, Day 8, Day 22, Day 43, Day 202

    Pre-vaccination, 1 and 3 weeks post-vaccination 1, and 3 weeks and 6 months post-vaccination 2

    Note: The Overall Number of Participants Analyzed (N) represents the total number of participants in the PPS; definitions are provided in the SAP. The Number Analyzed (n) at each timepoint corresponds to the number of participants with an available serum analysis result for the relevant strain at that timepoint. Instances where n<N reflect missing serum samples or non-evaluable results. All participants included in the Overall Number of Participants Analyzed contributed data to the analysis at one or more timepoints.

  4. Percentage of Subjects With Seroconversion Against the H5N1 Strain

    Time frame: Day 8, Day 22, Day 43, Day 202

    Seroconversion 1 and 3 weeks post-vaccination 1, and 3 weeks and 6 months post-vaccination 2, defined as a ≥4-fold increase in HI titer post-vaccination in those with pre-vaccination titer ≥1:10, or a post-vaccination HI titer ≥1:40 for subjects with baseline titer <1:10

    Note: The Overall Number of Participants Analyzed (N) represents the total number of participants in the PPS; definitions are provided in the SAP. The Number Analyzed (n) at each timepoint corresponds to the number of participants with an available serum analysis result for the relevant strain at that timepoint. Instances where n<N reflect missing serum samples or non-evaluable results. All participants included in the Overall Number of Participants Analyzed contributed data to the analysis at one or more timepoints.

  5. GMT of HI Antibodies Against the H5N6 Strain

    Time frame: Day 202

    GMT 6 months post-vaccination 2

  6. GMFI of HI Antibodies Against the H5N6 Strain

    Time frame: Day 1, Day 202

    GMFI 6 months post-vaccination 2 compared to pre-vaccination (Day 1)

  7. Percentage of Subjects With HI Titers ≥1:40 Against the H5N6 Strain

    Time frame: Day 202

    6 months post-vaccination 2

  8. Percentage of Subjects With Seroconversion Against the H5N6 Strain

    Time frame: Day 202

    Seroconversion 6 months post-vaccination 2, defined as a ≥4-fold increase in HI titer post-vaccination in those with pre-vaccination titer ≥1:10, or a post-vaccination HI titer ≥1:40 for subjects with baseline titer <1:10

  9. Frequency and Severity of Solicited Local and Systemic Adverse Events (AEs)

    Time frame: Day 1 through Day 7 and Day 22 through Day 28

    For 7 days following each vaccination

  10. Frequency and Severity of Unsolicited AEs

    Time frame: Day 1 through Day 43

    For 3 weeks following each vaccination

  11. Frequency of Serious AEs (SAEs), AEs Leading to Withdrawal, AEs of Special Interest (AESI) and Medically Attended AEs (MAAEs)

    Time frame: Day 1 through Day 202

    From vaccination until study completion

Sponsors and collaborators

Lead sponsor

Seqirus

Industry

Registry information

Official study title

A Phase 2, Randomized, Study to Evaluate Safety and Immunogenicity of One or Two Heterologous Booster Vaccinations With an MF59-adjuvanted, Cell Culture-derived H5N6 Influenza Vaccine in Adults Primed With MF59-adjuvanted, Cell Culture-derived H5N1 Influenza Vaccine or Unprimed

Important dates

Study start
2022
Primary completion
2022
Study completion
2023
First posted
Jun 16, 2022
Registry last updated
May 13, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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