Phase IV multicenter trial to evaluate the immunogenicity and safety of the Seqirus licensed zoonotic influenza vaccine (H5N8) in adults previously vaccinated with an H5N1/MF59 influenza vaccine, approximately 20 years before the trial, compared to adult participants never vaccinated with a H5 vaccine.

Overview

Sponsor-declared trial summary

Key facts

Sponsor

University Of Antwerp

Participant type

Healthy volunteers

Age range

18-64 years, 65+ years

Gender

Male and Female

Therapeutic area

Diseases [C] - Virus Diseases [C02]

Trial duration

8 Dec 2025 → 9 Apr 2026

Decision date (initial)

2025-10-06

Transition trial

No

Low-intervention

No

Rare-disease indication

No

Vulnerable population

No

Funding sources

European Vaccine Hub

Trial design

CTIS Part I — objectives, methods, condition coding

Main objective

Scope: Others, Safety

To evaluate the humoral immune response to the Seqirus zoonotic influenza vaccine in participants previously primed with the Novartis H5N1 influenza vaccine, as well as in H5N1 vaccine-naïve participants

Secondary objectives 3

1. To evaluate the humoral immune response to the Seqirus zoonotic influenza vaccine in participants previously primed with the Novartis H5N1 influenza vaccine, as well as in H5N1 vaccine-naïve participants
2. To evaluate the heterologous humoral immune response to the Seqirus zoonotic influenza vaccine in participants previously primed with the Novartis H5N1 influenza vaccine, as well as in H5N1 vaccine-naïve participants
3. To evaluate the safety of the Seqirus zoonotic influenza vaccine in participants previously primed with the Novartis H5N1 influenza vaccine, as well as in H5N1 vaccine-naïve participants

Conditions and MedDRA coding

Avian Influenza

Study design 1 period

Regulatory references

Plan to share IPD

No

Eligibility criteria

Principal inclusion / exclusion criteria as submitted by sponsor

Inclusion criteria 8

1. Participants, who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g. report adverse events, return for follow-up visits)
2. Written or witnessed informed consent obtained from the participant (participant must be able to understand the informed consent) prior to performance of any study-specific procedure.
3. A male or female aged 40 to 75 years at the time of the study intervention administration.
4. Participants who are medically stable in the opinion of the investigator at the time of the study intervention administration. Participants with chronic stable medical conditions with or without specific treatment, such as hypertension or cardiac disease, are allowed to participate in this study if considered by the investigator as medically stable and without potential influence on the immune response as to the opinion of the investigator.
5. Female participants of non-childbearing potential (WONCBP) may be enrolled in the study. Non-childbearing potential is defined as hysterectomy, bilateral oophorectomy, bilateral salpingectomy, and post-menopause*. *A postmenopausal state is defined as no menses for 12 months without an alternative medical cause. A high follicle stimulating hormone (FSH) level in the postmenopausal range may be used to confirm a postmenopausal state in women not using hormonal contraception or hormonal replacement therapy. However, in the absence of 12 months of amenorrhea, a single FSH measurement is insufficient.
6. Female participants of childbearing potential (WOCBP) may be enrolled in the study if the participant meets both of the following criteria: a. has practiced adequate contraception from 1 month prior to study intervention administration and agreed to continue adequate contraception until the end of the study. Adequate methods of contraception are enumerated in section 11.3. b. is not pregnant at the day of the study intervention administration, as per the medical anamnesis and urine pregnancy test.
7. Specific inclusion criteria for the H5N1 vaccine-exposed group. Participants who have previously received two or three doses of the M59-adjuvanted H5N1 vaccine in the V87P1 study and its extension, V87P1E1.
8. Specific inclusion criteria for the H5N1 vaccine-naive group. Participants who have never received a H5N1 or H5 containing vaccine.

Exclusion criteria 19

1. Known or suspected history of allergic reaction or hypersensitivity to any component of the study vaccine and/or likely to be exacerbated by egg, chicken protein, ovalbumin, formaldehyde, hydrocortisone, kanamycin, neomycine sulphate, cetyltrimethylammonium bromide (CTAB).
2. Any confirmed or suspected immunosuppressive condition, resulting from disease (e.g.,current malignancy, human immunodefiency virus) or immunosuppressive/cytotoxic therapy (e.g., medication used during cancer chemotherapy, organ transplantation, or to treat autoimmune disorders), based on medical history and physical examination (no laboratory required).
3. Recurrent history of uncontrolled neurological disorders or seizures. Participants with medically controlled active or chronic neurological diseases can be enrolled in the study as per investigator assessment, provided that their condition will allow them to comply with the requirements of the protocol.
4. Serious or unstable chronic illness.
5. Any history of dementia or any medical condition that moderately or severely impairs cognition.
6. Significant underlying illness that in the opinion of the investigator would be expected to prevent completion of the study.
7. Any medical condition that in the judgment of the investigator would make intramuscular injection unsafe.
8. Any SAE attributed to a previous dose of an influenza vaccine.
9. Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the study.
10. Use of any investigational or non-registered product (drug, vaccine, or invasive medical device) other than the study intervention during the period beginning 30 days before the administration of the study intervention and ending at the completion of the study.
11. Planned administration of a live attenuated vaccine in the period starting 30 days before the study intervention administration and ending at the completion of the study.
12. Chronic administration of immune-modifying drugs (defined as more than 14 consecutive days in total) and/or planned use of long-acting immune-modifying treatments at any time up to the completion of the study. a. Up to 3 months prior to the study intervention administration: i. For corticosteroids, this will mean prednisone equivalent ≥ 20 mg/day. Inhaled and topical steroids are allowed. ii. Administration of immunoglobulins and/or any blood products or plasma derivatives. b. Up to 6 months prior to the study intervention administration: long-acting immunemodifying drugs including among other immunotherapy (e.g., TNF-inhibitors), monoclonal antibodies and antitumoral medication.
13. Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational intervention (drug/invasive medical device).
14. Pregnant or lactating female participant.
15. Female participant planning to become pregnant or planning to discontinue contraceptive precautions.
16. History of chronic alcohol consumption and/or drug abuse as deemed by the investigator to render the potential participant unable/unlikely to provide accurate safety reports or comply with study procedures.
17. Body Mass Index < 18.0 or > 30.0 kg/m2.
18. Presence of a tattoo on the study intervention administration site that would prevent the assessment of the occurrence of local adverse events.
19. Participation of any study personnel or their immediate dependents, family, or household members.

Endpoints

Primary and secondary outcome measures (English text)

Primary endpoints 2

1. HI antibody titers against the vaccine virus strain (H5N8 clade 2.3.4.4b) at baseline (Day 0) and 28 days after the first dose, and 28 days after the second dose (Day 56)
2. MN antibody titers against the vaccine virus strain (H5N8 clade 2.3.4.4b) at baseline (Day 0), 28 days after the first dose, and 28 days after the second dose (Day 56)

Secondary endpoints 14

1. HI antibody titers against the vaccine virus strain (H5N8 clade 2.3.4.4b) 7 days after the first dose, and 7 days after the second dose (Day 35)
2. Fold increase in HI antibody titers against the virus strain (H5N8 clade 2.3.4.4b) 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day 56), compared to baseline (Day 0)
3. Serodetection, based on HI antibody titers against the virus strain (H5N8 clade 2.3.4.4b) at baseline (Day 0), 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day 56)
4. Seroconversion, based on HI antibody titers against the virus strain (H5N8 clade 2.3.4.4b) 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day 56), compared to baseline (Day 0)
5. Seroprotection, based on HI antibody titers against the virus strain (H5N8 clade 2.3.4.4b) at baseline (Day 0), 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day 56)
6. MN antibody titers against the vaccine virus strain (H5N8 clade 2.3.4.4b) 7 days after the first dose, and 7 days after the second dose (Day 35)
7. HI antibody titers against heterologous virus strains (including but not limited to H5N1 clade 1 A/Vietnam/1194/2004 and H5N1 clade 2.2.1 A/turkey/Turkey/1/2005) at baseline (Day 0), 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day 56)
8. Fold increase in HI antibody titers against heterologous virus strains (including but not limited to H5N1 clade 1 A/Vietnam/1194/2004 and H5N1 clade 2.2.1 A/turkey/Turkey/1/2005) 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 56), compared to baseline (Day 0)
9. Serodetection, based on HI antibody titers against heterologous virus strains (including but not limited to H5N1 clade 1 A/Vietnam/1194/2004 and H5N1 clade 2.2.1 A/turkey/Turkey/1/2005) at baseline (Day 0), 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day 56)
10. Seroconversion, based on HI antibody titers against heterologous virus strains (including but not limited to H5N1 clade 1 A/Vietnam/1194/2004 and H5N1 clade 2.2.1 A/turkey/Turkey/1/2005) 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day 56), compared to baseline (Day 0)
11. Seroprotection, based on HI antibody titers against heterologous virus strains (including but not limited to H5N1 clade 1 A/Vietnam/1194/2004 and H5N1 clade 2.2.1 A/turkey/Turkey/1/2005) at baseline (Day 0), 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day56)
12. MN antibody titers against heterologous virus strains (including but not limited to H5N1 clade 1 A/Vietnam/1194/2004 and H5N1 clade 2.2.1 A/turkey/Turkey/1/2005) at baseline (Day 0), 7 days and 28 days after the first dose, and 7 days and 28 days after the second dose (Day 35, Day 56)
13. Occurrence of all SAEs from the day of vaccination up to the study end
14. Occurrence of all SAEs related to study intervention from the day of vaccination up to the study end

Investigational products

Investigational medicinal products (IMPs), comparators, placebo, auxiliary

Test 1

Sponsors and contacts

Sponsor organisations, regulatory contacts, third parties

University Of Antwerp

Sponsor organisation

University Of Antwerp

Address

Drie Eikenstraat 663

City

Edegem

Postcode

2650

Country

Belgium

Scientific contact point

Organisation

University Of Antwerp

Contact name

Ilse De Coster

Public contact point

Organisation

University Of Antwerp

Contact name

Ilse De Coster

Third parties 7

Locations

2 EU/EEA countries · 2 investigational sites

By country

Investigational sites

Country notifications

Trial-start, recruitment-start, end and early-termination notifications submitted per Member State

Results and documents

Annex IV summary of results, Annex V layperson summary, and all documents registered in CTIS for this trial

Documents 37 files

Public protocol annexes, IB summaries, regulatory submissions and post-authorisation documents registered in CTIS.

Application history

1 submissions — initial application plus substantial / non-substantial modifications