Last updated: 09/25/2026 11:10:53
A Study to Evaluate the Immune Response and Safety of a Vaccine Against Influenza in adults 18-64 Years of age
GSK study ID
218132
Clinicaltrials.gov ID
Not applicable
EudraCT ID
Not applicable
EU CT Number
Trial status
Not yet recruiting
Not yet recruiting
Trial overview
Official title: A Phase 3 Randomized, Observer-Blind, Controlled Study to Evaluate the Immunogenicity, Reactogenicity and Safety of an mRNA-based Seasonal Influenza Vaccine, in adults 18-64 Years of age
Trial description: This clinical trial will study an investigational seasonal influenza vaccine in adults 18 to 64 years of age. The vaccine is based on messenger ribonucleic acid, also called mRNA. The main goals of the study are to learn how well the vaccine helps the body make an immune response against influenza and what medical problems participants may have after vaccination. Researchers will also compare immune responses in adults 18 to 64 years of age from this study, with immune responses in adults 65 years of age and older from another study. Participants will receive 1 injection into the upper arm muscle and will be followed for about 6 months.
Primary purpose:
Prevention
Trial design:
Parallel Assignment
Masking:
Triple (Participant, Investigator, Outcomes Assessor)
Allocation:
Randomized
Primary outcomes:
Geometric Mean Titer (GMT) of Antigen 1 Titer
Timeframe: At Day 29
GMT of Antigen 2 Titer
Timeframe: At Day 29
Percentage of participants with Antigen 1 seroconversion rate (SCR)
Timeframe: From Day 1 to Day 29
Number of participants with solicited administration site adverse events
Timeframe: Day 1 to Day 7
Number of participants with systemic adverse events
Timeframe: Day 1 to Day 7
Number of participants with unsolicited adverse events
Timeframe: Day 1 to Day 28
Number of participants with serious adverse events (SAEs)
Timeframe: Day 1 to Day 181
Number of participants with adverse events of special interest (AESIs)
Timeframe: Day 1 to Day 181
Number of Participants with any Laboratory abnormalities
Timeframe: At Day 1 (pre-dose) and at Day 29 (post - dose)
Secondary outcomes:
GMT of Antigen 1 and Antigen 2 antibodies
Timeframe: At Day 29
Percentage of Participants with Antigen 1 and Antigen 2 antibodies SCR
Timeframe: Day 1 to Day 29
Geometric Mean Increase (GMI) of Antigen 1 Titer
Timeframe: At Day 29 relative to baseline (Day 1)
GMI of Antigen 2 Titer
Timeframe: At Day 29 relative to baseline (Day 1)
Percentage of Participants with Antigen 1 Seroprotection Rate (SPR)
Timeframe: At Day 1 and Day 29
Percentage of Participants with Antigen 2 SCR
Timeframe: Day 1 to Day 29
GMT of virus neutralization titers
Timeframe: At Day 29
Percentage of participants with seroconversion of virus neutralization titers
Timeframe: Day 1 to Day 29
GMI of virus neutralization titers
Timeframe: At Day 29 relative to baseline (Day 1)
Interventions:
Biological/vaccine: mRNA Seasonal Flu vaccine
Biological/vaccine: Comparator 1
Biological/vaccine: Comparator 2
Enrollment:
3000
Primary completion date:
2027-09-07
Observational study model:
Not applicable
Time perspective:
Not applicable
Clinical publications:
Not applicable
Medical condition
Influenza, Human
Product
Not applicable
Collaborators
Not applicable
Study date(s)
October 2026 to July 2027
Type
Interventional
Phase
3
Participation criteria
Sex
Female & Male
Age
18 - 64 Years
Accepts healthy volunteers
Yes
- Participants who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g., completion of the eDiary, return for follow-up visits, attendance to study contacts, and ability to access and utilize a phone or other electronic communications) independently or with the assistance of a caregiver.
- A male or female participant between and including 18 to 64 years of age at the time of study intervention administration
- History of test confirmed influenza infection within 180 days prior to study intervention administration.
- Confirmed or suspected immunosuppressive or immunodeficient condition, except for stable human immunodeficiency virus infection meeting protocol-defined stability criteria.
Inclusion and exclusion criteria
Inclusion criteria:
- A male or female participant between and including 18 to 64 years of age at the time of study intervention administration
- Participants of childbearing potential may be enrolled, if the participant:
- has practiced adequate contraception for at least 30 days prior to study intervention administration, and
- has a negative urine pregnancy test within 24 hours prior to study intervention administration, and
- has agreed to continue adequate contraception for at least 8 weeks after study intervention administration.
Participants who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g., completion of the eDiary, return for follow-up visits, attendance to study contacts, and ability to access and utilize a phone or other electronic communications) independently or with the assistance of a caregiver.
Exclusion criteria:
- Confirmed or suspected immunosuppressive or immunodeficient condition, except for stable human immunodeficiency virus infection meeting protocol-defined stability criteria.
- History of myocarditis or pericarditis considered causally associated with the administration of an mRNA vaccine.
- History of hypersensitivity or allergic reaction to any previous influenza vaccine.
- History of hypersensitivity or allergic reaction to any previous mRNA vaccine.
- History of Guillain-Barré syndrome (GBS) within 6 weeks of receiving any vaccine.
- Acute or unstable chronic conditions as determined by medical history and clinical examination.
- Administration of an influenza vaccine in the period starting 180 days before the study intervention administration or planned administration prior to Visit 2 during the study.
- Planned administration/administration of prohibited vaccines within protocol-defined time windows before or after study intervention administration.
- Use of any investigational or non-registered product (other than the study intervention during the period beginning 30 days before the dose of study intervention (Day -29 to Day 1), or their planned use during the study period.
- 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 end of the study.
- Pregnant or lactating female participant.
History of test confirmed influenza infection within 180 days prior to study intervention administration.
Trial location(s)
No location data available.
Study documents
No study documents available.
Results overview
Study Results yet to be posted
Recruitment status
Not yet recruiting
Actual primary completion date
Not applicable
Actual study completion date
Not applicable
Plain language summaries
Plain language summaries of clinical trial results for Phase 2-4 clinical trials that were initiated on or after January 2022 will be posted by GSK within one year following study completion.
Additional information about the trial
Additional information
Not applicable
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