NCT07275060

Brief Summary

Given the recent circulation of avian influenza A(H5N1) clade 2.3.4.4b strains in birds and mammals in North America, Canada procured a supply of Arepanrix™ H5N1 for potential use in persons at high risk of highly pathogenic avian influenza exposure. This vaccine received regulatory approval in 2013, to be given in two doses at least 3 weeks apart. There is limited data on the effect of various intervals between the two doses on immunogenicity and tolerability. In this study two intervals between doses will be compared (3 vs. 8 weeks apart).

Trial Health

75
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
312

participants targeted

Target at P75+ for phase_4

Timeline
17mo left

Started Oct 2025

Geographic Reach
1 country

4 active sites

Status
active not recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

Study Progress29%
Oct 2025Sep 2027

Study Start

First participant enrolled

October 14, 2025

Completed
1 month until next milestone

First Submitted

Initial submission to the registry

November 16, 2025

Completed
24 days until next milestone

First Posted

Study publicly available on registry

December 10, 2025

Completed
1.2 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

February 28, 2027

Expected
7 months until next milestone

Study Completion

Last participant's last visit for all outcomes

September 30, 2027

Last Updated

January 16, 2026

Status Verified

January 1, 2026

Enrollment Period

1.4 years

First QC Date

November 16, 2025

Last Update Submit

January 15, 2026

Conditions

H5N1 InfluenzaH5N1 VirusAvian InfluenzaAvian Influenza A Virus

Keywords

clinical trialavian fluH5N1vaccine

Outcome Measures

Primary Outcomes (1)

  • Percentages of participants with seroprotection against the H5N1 2.3.4.4b clade vaccine given 3 vs. 8 weeks apart

    Percentages of participants with seroprotection against the H5N1 2.3.4.4b clade 28 days following administration of 2 doses of avian influenza A(H5N1) vaccine given 3 vs. 8 weeks apart based on serologic outcomes at visit 4 (approximately week 12). Seroprotection is defined as the proportion of subjects who were either seronegative prior to vaccination and have a protective post-vaccination HI titre of ≥ 1:40 or who were seropositive prior to vaccination and have at least a 4-fold increase in HI titre post-vaccination.

    28 days post-administration of 2 doses of avian influenza A (H5N1 (Approximately week 12).

Secondary Outcomes (5)

  • Immunogenicity - Percentages of participants with seroconversion and the geometric mean fold rise against the H5N1 2.3.4.4b clade vaccine given 3 vs. 8 weeks apart.

    28 days post-administration of 2 doses of avian influenza A (H5N1)

  • Immunogenicity - GMT of HI against the H5N1 2.3.4.4b clade vaccine given 3 vs. 8 weeks apart.

    28 days post-administration of 2 doses of avian influenza A (H5N1) vaccine

  • Immunogenicity - Percentages of participants with seroprotection, seroconversion and the geometric mean fold rise against the H5N1 2.3.4.4b clade

    at baseline, at 3 weeks, at 8 weeks, 12 weeks, 26 weeks and through study completion (average of 1 year).

  • Immunogenicity - Percentages of participants with seroprotection, seroconversion and the geometric mean fold rise against the H5N1 2.3.4.4b clade

    6 and 12 months after the first dose of avian influenza A (H5N1) vaccine

  • Incidence of Grade 3 & 4 Adverse Events

    Up to 12 months after the first dose of avian influenza A (H5N1) vaccine

Study Arms (2)

Group 1: H5N1 vaccines administered 3 weeks apart

ACTIVE COMPARATOR

Two doses of the H5N1 vaccine administered 3 weeks apart. Normal saline will be administered as a placebo at week 8.

Biological: H5N1 vaccine (Arepanrix)Other: Saline (as a placebo)

Group 2: H5N1 vaccines administered 8 weeks apart

ACTIVE COMPARATOR

Two doses of the H5N1 vaccine administered 8 weeks apart Normal saline will be administered as a placebo at week 3.

Biological: H5N1 vaccine (Arepanrix)Other: Saline (as a placebo)

Interventions

H5N1 vaccine (Arepanrix)BIOLOGICAL

The H5N1 (Arepanrix) vaccine will be administered according to the Product Monograph.

Also known as: Arepanrix, GSK
Group 1: H5N1 vaccines administered 3 weeks apartGroup 2: H5N1 vaccines administered 8 weeks apart
Saline (as a placebo)OTHER

Normal saline will be administered as a placebo according to the Product Monograph.

Also known as: Normal Saline
Group 1: H5N1 vaccines administered 3 weeks apartGroup 2: H5N1 vaccines administered 8 weeks apart

Eligibility Criteria

Age18 Years - 59 Years
Sexall
Healthy VolunteersYes
Age GroupsAdult (18-64)

You may qualify if:

  • Individuals in stable health (defined as no new onset or exacerbation of pre-existing chronic disease three months prior to vaccination) 18-59 years of age.
  • Able to comply with the trial procedures.
  • Informed consent signed prior to trial-specific procedures.
  • If a person is at risk of becoming pregnant, has practiced adequate contraception for 28 days prior to visit 1, and has a negative pregnancy test on the day of vaccination and has agreed to continue adequate contraception until 60 days after the final vaccination.
  • Risk of pregnancy is defined as any cis woman and/or gender divergent individual assigned female at birth or with reproductive capacity who is sexually active with individuals with sperm-producing capabilities.
  • Individual who are post-menopausal or permanently sterile (hysterectomy, bilateral salpingectomy) are not considered at risk of pregnancy. A post-menopausal state is defined as a no menses for 12 months.
  • Effective contraception methods are:
  • Combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation:
  • Oral
  • Intravaginal
  • Transdermal
  • Progestogen-only hormonal contraception associated with inhibition of ovulation:
  • Oral
  • Injectable
  • Implantable
  • +15 more criteria

You may not qualify if:

  • Any of the following:
  • Receipt of avian influenza A(H5N1) vaccine anytime.
  • Positive pregnancy test prior to vaccination, or breastfeeding.
  • Receipt of immunoglobulins and/or any blood products within 3 months preceding the first dose of study vaccine and for one month after the last dose of study vaccine (except Rho D).
  • Bleeding disorder or history of significant bleeding following IM injections or venipuncture.
  • Any confirmed or suspected immunosuppressive or immunodeficient state; asplenia, or immunosuppressant medication within the past 6 months except short term oral steroids (≤14 days duration) or topical steroids.
  • Unstable chronic medical condition requiring ongoing follow-up and monitoring by a physician as determined by the investigator.
  • History of anaphylaxis or allergy to any of the constituents or trace residues of the study vaccine, including egg protein.
  • Receipt of non-study vaccine(s) 2 weeks prior to the study vaccine or planned 2 weeks after administration of the study vaccine.

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (4)

Vaccine Evaluation Center

Vancouver, British Columbia, Canada

Location

Canadian Center for Vaccinology

Halifax, Nova Scotia, Canada

Location

Vaccine Study Centre of the McGill University Health Centre

Pierrefonds, Quebec, H9H 4Y6, Canada

Location

CHU de Québec

Québec, Quebec, G1E 7G9, Canada

Location

Related Links

MeSH Terms

Conditions

Influenza in Birds

Interventions

arepanrixSodium ChlorideSaline Solution

Condition Hierarchy (Ancestors)

Orthomyxoviridae InfectionsRNA Virus InfectionsVirus DiseasesInfectionsBird DiseasesAnimal Diseases

Intervention Hierarchy (Ancestors)

ChloridesHydrochloric AcidChlorine CompoundsInorganic ChemicalsSodium CompoundsCrystalloid SolutionsIsotonic SolutionsSolutionsPharmaceutical Preparations

Study Officials

  • Joanne M Langley

    CIRN, Canadian Center for Vaccinology, Dalhousie University

    PRINCIPAL INVESTIGATOR

Study Design

Study Type
interventional
Phase
phase 4
Allocation
RANDOMIZED
Masking
QUADRUPLE
Who Masked
PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
Purpose
PREVENTION
Intervention Model
PARALLEL
Sponsor Type
NETWORK
Responsible Party
PRINCIPAL INVESTIGATOR
PI Title
Principal Investigator

Study Record Dates

First Submitted

November 16, 2025

First Posted

December 10, 2025

Study Start

October 14, 2025

Primary Completion (Estimated)

February 28, 2027

Study Completion (Estimated)

September 30, 2027

Last Updated

January 16, 2026

Record last verified: 2026-01

Locations

CA(4)