NCT07851246 · GlaxoSmithKline
A Study to Evaluate the Immune Response and Safety of a Vaccine Against Influenza in Adults 18-64 Years of Age
What this study is about
This clinical trial will study an experimental 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.
View original scientific 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.
Interventions
BIOLOGICAL
mRNA Seasonal Flu vaccine
One dose of the mRNA Flu vaccine received intramuscularly.
BIOLOGICAL
Comparator 1
One dose of the comparator vaccine received intramuscularly.
BIOLOGICAL
Comparator 2
One dose of the comparator vaccine received intramuscularly.
Primary outcome measures
Geometric Mean Titer (GMT) of Antigen 1 Titer
Time frame: At Day 29
GMT of Antigen 2 Titer
Time frame: At Day 29
Percentage of participants with Antigen 1 seroconversion rate (SCR)
Time frame: From Day 1 to Day 29
Number of participants with solicited administration site adverse events
Time frame: Day 1 to Day 7
Number of participants with systemic adverse events
Time frame: Day 1 to Day 7
Number of participants with unsolicited adverse events
Time frame: Day 1 to Day 28
Number of participants with serious adverse events (SAEs)
Time frame: Day 1 to Day 181
Number of participants with adverse events of special interest (AESIs)
Time frame: Day 1 to Day 181
Number of Participants with any Laboratory abnormalities
Time frame: At Day 1 (pre-dose) and at Day 29 (post - dose)
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- 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
- 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.
Exclusion criteria
- 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.
- 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.
Where
- Glendale, Arizona
- Tucson, Arizona
- San Diego, California
- Miami, Florida
- Miami Lakes, Florida
- Meridian, Idaho
- Valparaiso, Indiana
- Lenexa, Kansas
- Hartsdale, New York
- Spartanburg, South Carolina
- DeSoto, Texas
- Fort Worth, Texas
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Oct 9, 2026 · Source of record for eligibility and locations