Recruiting

Phase 3

mRNA VaccineA Study to Evaluate the Immune Response and Safety of a Vaccine Against Influenza in Adults 18-64 Years of Age

Sponsor:

GlaxoSmithKline

Code:

NCT07851246

Conditions

Influenza, Human

Eligibility Criteria

Sex: All

Age: 18 - 64

Healthy Volunteers: Accepted

Interventions

mRNA Seasonal Flu vaccine

Comparator 1

Comparator 2

Study Details

Brief summary:

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.

Conditions

Influenza, Human

Study ID

NCT07851246

Start date

Oct 1, 2026

Status verified date

Oct, 2026

Completion date

Jul 9, 2027

Anticipated

Primary completion date

Jul 9, 2027

Anticipated

Eligibility Criteria

Sex: All

Age: 18 - 64

Healthy Volunteers: Accepted

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.

Study Design

Enrollment

3000 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

experimental: mRNA Seasonal Flu Vaccine - Cohort 1

Participants 18 to 64 years of age will receive a single dose of investigational mRNA Seasonal Flu vaccine on Day 1.

active comparator: Comparator 1 Cohort 1

Participants 18 to 64 years of age will receive a single dose of comparator 1 on Day 1.

experimental: mRNA Seasonal Flu Vaccine - Cohort 2

Participants 60 to 64 years of age will receive a single dose of investigational mRNA Seasonal Flu vaccine on Day 1.

active comparator: Comparator 2 Cohort 2

Participants 60 to 64 years of age will receive a single dose of comparator 2 on Day 1.

Interventions

mRNA Seasonal Flu vaccine

One dose of the mRNA Flu vaccine received intramuscularly.

Comparator 1

One dose of the comparator vaccine received intramuscularly.

Comparator 2

One dose of the comparator vaccine received intramuscularly.

Primary outcome measure

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) ]

Central Contacts and Locations

Central contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Center

+44 (0) 20 89904466 GSKClinicalSupportHD@gsk.com

Locations

GSK Investigational Site

Recruiting

Glendale, Arizona, United States, 85308

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Abram Burgher

GSK Investigational Site

Recruiting

Tucson, Arizona, United States, 85711

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Anita Kohli

GSK Investigational Site

Recruiting

San Diego, California, United States, 92123

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Donald Brandon

GSK Investigational Site

Recruiting

Miami, Florida, United States, 33186

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Rafael Ubeda

GSK Investigational Site

Recruiting

Miami Lakes, Florida, United States, 33016

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Jose Cardona

GSK Investigational Site

Recruiting

Meridian, Idaho, United States, 83642-3154

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Mark Turner

GSK Investigational Site

Recruiting

Valparaiso, Indiana, United States, 46383

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Robert Buynak

GSK Investigational Site

Recruiting

Lenexa, Kansas, United States, 66219

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Carlos Fierro

GSK Investigational Site

Recruiting

Hartsdale, New York, United States, 10530

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Michael Gerdis

GSK Investigational Site

Recruiting

Spartanburg, South Carolina, United States, 29303

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Charles Fogarty

GSK Investigational Site

Recruiting

DeSoto, Texas, United States, 75115

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

Haresh Boghara

GSK Investigational Site

Recruiting

Fort Worth, Texas, United States, 76135

Contacts

US GSK Clinical Trials Call Center

877-379-3718 GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Centre

+44 (0) 20 8990 4466 GSKClinicalSupportHD@gsk.com

Principal Investigator:

William Seger

More Information

Sponsor

GlaxoSmithKline

Last update posted

Oct 9, 2026

Last verified

Oct, 2026

Keywords

Influenza;
Seasonal influenza vaccine;
Messenger ribonucleic acid vaccine;
mRNA vaccine;
Immunogenicity;
Reactogenicity;
Safety

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-10. This information was provided to ClinicalTrials.gov by GlaxoSmithKline on 2026-10-09. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.