A Phase 3 interventional study of mRNA Seasonal Flu vaccine and Licensed Influenza Vaccine in Influenza, Human, sponsored by GlaxoSmithKline. Recruiting at 163 sites in United States. Open to participants aged 65 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-18.
Sponsored by GlaxoSmithKline · Phase 3, Interventional, and Prevention
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Among 187 studies in Influenza, Human by GlaxoSmithKline — 3 open to participants now, 3 under way, 2 of them phase 3. Influenza, Human · GlaxoSmithKline.
Among the 187 studies in Influenza, Human by GlaxoSmithKline, this one has the largest planned enrollment of the 165 interventional ones that give a count, is one of 3 that started in 2026, is one of 74 in phase 3, and was the 186th registered.
2,358 studies on the registry are indexed under Influenza, Human; 184 are open to participants now.
Browse Influenza, Human studies →3 of the 187 studies in Influenza, Human by GlaxoSmithKline are open now, in 1 country. Recruiting first, the newest first:
GlaxoSmithKline · Sites in United States
Ages 18–64 · Healthy volunteers
GlaxoSmithKline · Sites in United States
Ages 65–85
By country, each count listing its studies:
Of the 121 Influenza, Human studies recruiting now, 66 (55%) set no upper age limit and 45 (37%) stop at 75 or younger; 33 take children under 18; 67 take healthy volunteers.
This study: 65 Years and older · all sexes · healthy volunteers too.
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187 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 25 · Phase 2 56 · Phase 3 74 · Phase 4 12
First in 2002; this study’s year is marked. 3 started in 2026.
By drug class, each counting the studies that test any of its medicines:
This study's planned enrollment of 54,000 is above the median of 227 across 1,957 interventional studies indexed under Influenza, Human.
Median enrollment 324 across the 165 interventional studies, 605 across the 22 observational. Of the 178 that completed or were terminated, 132 (74%) have results posted.
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GlaxoSmithKline is the lead sponsor of 3,650 studies on the registry; 117 are open to participants now.
Of its 265 completed or terminated interventional studies of FDA-regulated products, 241 (91%) have results posted.
2 of the studies in Influenza, Human by GlaxoSmithKline that are under way reach primary completion within a year, 1 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT07851246Phase 3GlaxoSmithKlineA Study to Evaluate the Immune Response and Safety of a Vaccine Against Influenza in Adults 18-64 Years of Age | 2027-07-09 |
| NCT07464314GlaxoSmithKlineA Study on the Safety and Immune Response of Investigational mRNA Seasonal Flu/COVID-19 Combination Vaccine in Adults | 2026-12-03 |
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Among the 187 studies in Influenza, Human by GlaxoSmithKline, from their registry updates:
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This study will compare an investigational mRNA flu vaccine with a licensed flu vaccine in adults 65 years of age and older. Participants will receive one injection and will be followed during the flu season. The study will measure prevention of laboratory-confirmed flu illness, side effects, and immune responses.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
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.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CD4 count
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Live vaccines
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive a single dose of investigational mRNA Seasonal Flu vaccine on Day 1.
Combination Product: mRNA Seasonal Flu vaccine
Participants will receive a single dose of an age-appropriate and season-adapted licensed influenza vaccine Day 1.
Combination Product: Licensed Influenza Vaccine
Single-dose intramuscular administration of the season-adapted investigational mRNA Seasonal Flu vaccine.
Single-dose intramuscular administration of an age-appropriate and season-adapted licensed influenza vaccine used as the active comparator.
Laboratory-confirmed protocol-defined influenza-like illness (ILI) assessed by incidence rate ratio
First occurrence of laboratory-confirmed protocol-defined ILI caused by influenza A subtypes and B lineage. Protocol-defined ILI is defined as the simultaneous occurrence of at least 1 respiratory symptom and at least 1 systemic symptom. Respiratory symptoms include nasal congestion, sore throat, new or increased sputum, new or increased cough, new or increased dyspnea, or wheezing. Systemic symptoms include temperature \>37.2°C/99°F or feverishness, fatigue, myalgia, or headache. The endpoint will be assessed using an incidence rate approach. Relative vaccine efficacy will be calculated as 100 × (1 - incidence rate ratio).
Time frame: From Day 15 through the end of the influenza Season
Number of Participants with Solicited Administration Site Adverse Events (AEs)
The solicited administration site AEs considered are pain, redness, swelling and lymphadenopathy. Lymphadenopathy is defined as localized axillary, cervical or supraclavicular swelling or tenderness ipsilateral to the injection arm.
Time frame: From Day 1 to Day 7
Number of Participants with Solicited Systemic AEs
The solicited systemic AEs considered are fever, headache, fatigue, myalgia, arthralgia and chills. Fever is defined as temperature greater than or equal to (\>=) 38 °C/100.4 °F regardless the location of measurement.
Time frame: From Day 1 to Day 7
Number of Participants with Unsolicited AEs
An unsolicited AE is an AE that was either not included in the list of solicited events or could be included in the list of solicited events but with an onset outside the specified period of follow-up for solicited events.
Time frame: From Day 1 to Day 28
Number of Participants with Serious Adverse Events (SAEs)
SAE is an AE which results in death, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in disability/incapacity, or other situations that are considered serious per medical or scientific judgment.
Time frame: From Day 1 up to the end of the influenza season (with at least 180 days of follow-up)
Number of Participants with Adverse Events of Special Interest (AESIs)
An adverse event of special interest is an adverse event of scientific and medical concern specific to the sponsor's product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor may be appropriate. AESIs include protocol-defined events such as potential immune-mediated disorders, myocarditis, pericarditis, severe hypersensitivity reactions, and other AESIs defined in the protocol.
Time frame: From Day 1 up to the end of the influenza season (with at least 180 days of follow-up)
Number of Participants with any Laboratory abnormalities
Time frame: At Day 1 (pre-dose) and at Day 29 (post -dose)
Laboratory-confirmed protocol-defined ILI assessed for relative vaccine efficacy by incidence rate ratio
First occurrence of laboratory-confirmed protocol-defined ILI caused by influenza A subtypes and B lineage. This endpoint will assess the incidence rate of the investigational mRNA Seasonal Flu vaccine compared with the licensed influenza vaccine comparator.
Time frame: From Day 15 through the end of the influenza Season
Severe Influenza Disease (SID) assessed by incidence rate ratio
First occurrence of severe influenza disease caused by influenza A or B. Severe influenza disease includes serious influenza-related outcomes such as pneumonia, hospitalization, or death associated with laboratory-confirmed influenza.
Time frame: From Day 15 through the end of the influenza Season
Laboratory-confirmed Centers for Disease Control and Prevention-defined ILI assessed by incidence rate ratio
First occurrence of laboratory-confirmed Centers for Disease Control and Prevention-defined ILI caused by influenza A subtypes and B lineage.
Time frame: From Day 15 through the end of the influenza Season
Laboratory-confirmed modified Centers for Disease Control and Prevention-defined ILI assessed by incidence rate ratio
First occurrence of laboratory-confirmed modified Centers for Disease Control and Prevention-defined ILI caused by influenza A subtypes and B lineage.
Time frame: From Day 15 through the end of the influenza Season
Laboratory-confirmed protocol-defined ILI by antigenic matching status
First occurrence of laboratory-confirmed protocol-defined ILI caused by influenza viruses considered antigenically matched, non-matched, or of unknown matching status to the vaccine strains.
Time frame: From Day 15 through the end of the influenza Season ,
All-cause protocol-defined ILI assessed by incidence rate ratio
First occurrence of protocol-defined ILI, regardless of cause.
Time frame: From Day 15 through the end of the influenza Season
Influenza-related medically attended event assessed by incidence rate ratio
First occurrence of an influenza-related medically attended event associated with laboratory-confirmed protocol-defined ILI or severe influenza disease.
Time frame: From Day 15 through the end of the influenza Season
Influenza-related oxygen support for more than 24 hours assessed by incidence rate ratio
First occurrence of influenza-related oxygen support for more than 24 hours associated with laboratory-confirmed protocol-defined ILI or severe influenza disease.
Time frame: From Day 15 through the end of the influenza Season
Influenza-related intensive care unit admission assessed by incidence rate ratio
First occurrence of influenza-related intensive care unit admission associated with laboratory-confirmed protocol-defined ILI or severe influenza disease.
Time frame: From Day 15 through the end of the influenza Season
Influenza-related major adverse cardiovascular event assessed by incidence rate ratio
First occurrence of influenza-related major adverse cardiovascular event associated with laboratory-confirmed protocol-defined ILI or severe influenza disease.
Time frame: From Day 15 through the end of the influenza Season
To evaluate the impact of the study interventions on healthcare resource utilization during laboratory-confirmed influenza episodes
Healthcare resource utilization during laboratory-confirmed protocol-defined ILI or severe influenza disease episodes. This includes hospitalization and length of stay, intensive care unit admission and length of stay, emergency room or urgent care visits, general practitioner or specialist visits, medical home visits, physical therapy sessions, use of antibiotics, antiviral medication, oxygen therapy, advanced oxygen support, mechanical ventilation, and number of days missed from work.
Time frame: From Day 15 through the end of the influenza Season
Geometric mean titers (GMT) Ratio of Antigen 1, Antigen 2 and Virus Neutralization Antibody Titers
Time frame: At Day 29
Geometric mean increase (GMI) of Antigen 1, Antigen 2 and Virus Neutralization Antibody Titers
Time frame: From Day 1 to Day 29
Percentage of Participants with Antigen 1, Antigen 2 and Virus Neutralization Seroconversion Rate (SCR)
Time frame: From Day 1 to Day 29
Percentage of Participants with Antigen 1 Seroprotection Rate (SPR)
Time frame: At Day 1 and Day 29
Showing the first 100 of 163 sites. Choose a country and city above to see the rest.
Plan to share: Yes — Study Sponsor will assess requests from qualified researchers for anonymized individual patient-level data and related study documents. Data sharing is subject to certain criteria, conditions, and exceptions. For further information, refer to https://www.gsk-studyregister.com/gsk-patient-level-data-sharing-july2025.pdf
Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Clinical study report
Time frame: Anonymized IPD will be made available within 6 months of publication of primary, key secondary and safety results for studies in product with approved indication(s) or asset(s) with development terminated across all indications.
Access criteria: Anonymized IPD is shared with researchers whose proposals are approved by an Independent Review Panel and after a Data Sharing Agreement is in place. Access is provided for an initial period of 12 months, but an extension may be granted, when justified, for up to 6 months.
Data sharing details ↗ · www.gsk-studyregister.com
No publications or documents are linked to this record.
Started Sep 2026 (actual). Primary completion is estimated for Jun 2028, 21 months after the start.
Of 119 industry-sponsored phase 3 interventional studies under Influenza, Human, half reached primary completion within 8 months of starting (the median), counting those still running; a quarter within 3 and three quarters within 14. This study's planned 21 months is above that.
Counting every sponsor, half of 154 studies reached it within 8 months; a quarter within 4 and three quarters within 15.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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