Influenza, HumanPhase 2NCT05422326

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

A Phase 2 study testing aH5N6c on Day 1 and aH5N6c on Day 22 in people with Influenza, Human and Influenza in Birds, run by Seqirus at 18 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

Who is it for?: Ages 18 years and olderHealthy volunteers can take part
Conditions the study is for: Influenza, Human, Influenza in Birds, Respiratory Tract Infections
What is being tested?: aH5N6c on Day 1 and aH5N6c on Day 22
Type of treatment: Vaccines, Injection or infusion
Could I receive a placebo?: Yes, some participants may receive a placebo
How many people: 260 participants
Where: 18 sitesUnited States
Study dates: 18 Jul 2022to 24 Mar 2023
Phase: Phase 2

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 years and older
All sexes
Healthy volunteers accepted
Adult, Older adult

Who may be able to join

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.

Who cannot join

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).

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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.

Trial locations and contacts

18 sites in 1 country.

City, postcode or hospital

18 sites in 1 country

United States18 sites

Great Lakes Clinical Trials LLC
Chicago, Illinois, 60640
Innovative Research of West Florida, Inc.
Clearwater, Florida, 33756
Aventiv Research
Columbus, Ohio, 43213
Optimal Research, LLC
Huntsville, Alabama, 35802
The Center for Pharmaceutical Research
Kansas City, Missouri, 64114
Optimal Research, LLC
Melbourne, Florida, 32934
Clinical Research Consulting, LLC
Milford, Connecticut, 06460
PMG Research of Raleigh
Raleigh, North Carolina, 27609
Rochester Clinical Research, Inc
Rochester, New York, 14609
J. Lewis Research, Inc/Foothill Family Clinic North
Salt Lake City, Utah, 84109
J. Lewis Research, Inc/Foothill Family Clinic South
Salt Lake City, Utah, 84121
Biogenics Research Institute
San Antonio, Texas, 78229
California Research Foundation
San Diego, California, 92103
J. Lewis Research, Inc/Jordan River Family Medicine
South Jordan, Utah, 84095
Sundance Clinical Research, LLC
St Louis, Missouri, 63141
Clinical Research Consortium Arizona
Tempe, Arizona, 85283
Heartland Research Associates, LLC
Wichita, Kansas, 67207
AccellaCare
Winston-Salem, North Carolina, 27103

Other trials in United States

About this study

Official 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

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.

Conditions: Influenza, Human, Influenza in Birds, Respiratory Tract Infections, Infections, Orthomyxoviridae Infections, RNA Virus Infections
Being tested: aH5N6c on Day 1, aH5N6c on Day 22, Placebo on Day 22
Keywords: Influenza, Pandemic, Vaccine, H5N1, H5N6, Flu, MF59, Avian
Medical subject headings: Influenza, Human, Influenza in Birds, Respiratory Tract Infections, Infections, Orthomyxoviridae Infections, RNA Virus Infections, Virus Diseases, Respiratory Tract Diseases

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

aH5N6c on Day 1Biological
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 22Biological
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 22Biological
Saline placebo (sterile, 0.5 mL) given 3 weeks after the aH5N6c vaccination

Study groups in NCT05422326
Study group	Role	What they receive
Group 1	Experimental	Eligible subjects who received 2 doses of aH5N1c in the parent study V89_18 and have been randomized to receive two aH5N6c vaccinations, 3 weeks apart Receives: Biological: aH5N6c on Day 1; Biological: aH5N6c on Day 22
Group 2	Experimental	Eligible subjects who received 2 doses of aH5N1c in the parent study V89_18 and have been randomized to receive an aH5N6c vaccination on Day 1 and saline placebo on Day 22 Receives: Biological: aH5N6c on Day 1; Biological: Placebo on Day 22
Group 3	Experimental	Eligible subjects who received placebo in the parent study V89_18 receive two aH5N6c vaccinations, 3 weeks apart. Receives: Biological: aH5N6c on Day 1; Biological: aH5N6c on Day 22

What is being measured

The primary outcome is the main question the study is designed to answer.

Geometric Mean Titer (GMT) of Hemagglutination Inhibition (HI) Antibodies Against the H5N6 Strain
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.
Measured: Day 1, Day 8, Day 22, Day 43
Geometric Mean Fold Increase (GMFI) of HI Antibodies Against the H5N6 Strain
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.
Measured: Day 1, Day 8, Day 22, Day 43
Percentage of Subjects With HI Titers ≥1:40 Against the H5N6 Strain
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.
Measured: Day 1, Day 8, Day 22, Day 43
Percentage of Subjects With Seroconversion Against the H5N6 Strain
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.
Measured: Day 8, Day 22, Day 43

Secondary outcomes (11)

GMT of HI Antibodies Against the H5N1 Strain
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.
Measured: Day 1, Day 8, Day 22, Day 43, Day 202
GMFI of HI Antibodies Against the H5N1 Strain
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.
Measured: Day 1, Day 8, Day 22, Day 43, Day 202
Percentage of Subjects With HI Titers ≥1:40 Against the H5N1 Strain
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.
Measured: Day 1, Day 8, Day 22, Day 43, Day 202
Percentage of Subjects With Seroconversion Against the H5N1 Strain
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.
Measured: Day 8, Day 22, Day 43, Day 202
GMT of HI Antibodies Against the H5N6 Strain
GMT 6 months post-vaccination 2
Measured: Day 202
GMFI of HI Antibodies Against the H5N6 Strain
GMFI 6 months post-vaccination 2 compared to pre-vaccination (Day 1)
Measured: Day 1, Day 202
Percentage of Subjects With HI Titers ≥1:40 Against the H5N6 Strain
6 months post-vaccination 2
Measured: Day 202
Percentage of Subjects With Seroconversion Against the H5N6 Strain
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
Measured: Day 202
Frequency and Severity of Solicited Local and Systemic Adverse Events (AEs)
For 7 days following each vaccination
Measured: Day 1 through Day 7 and Day 22 through Day 28
Frequency and Severity of Unsolicited AEs
For 3 weeks following each vaccination
Measured: Day 1 through Day 43
Frequency of Serious AEs (SAEs), AEs Leading to Withdrawal, AEs of Special Interest (AESI) and Medically Attended AEs (MAAEs)
From vaccination until study completion
Measured: Day 1 through Day 202

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

18 Jul 202224 Mar 2023

First posted16 Jun 2022
Study start18 Jul 2022
Primary completion24 Oct 2022
Study completion24 Mar 2023

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Other trials for Influenza, HumanStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 2
Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Model description: Eligible subjects, who received 2 doses of aH5N1c in the parent study V89\_18 are randomized in a 1:1 ratio to group 1 (two aH5N6c vaccinations, 3 weeks apart) or group 2 (aH5N6c vaccination and placebo, 3 weeks apart). Eligible subjects, who received placebo in the parent study are allocated to group 3 (two aH5N6c vaccinations, 3 weeks apart).
Masking: Triple blind
Who is masked: Participant, Investigator, Outcomes assessor
Enrolment: 260 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT05422326
Sponsor's protocol ID: V89_18E1
Status last verified: Oct 2025
First submitted: 14 Jun 2022
Last updated: 13 May 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: Undecided

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

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