A Study on the Safety and Immune Response of Investigational mRNA Seasonal Flu/COVID-19 Combination Vaccine in Adults

March 23, 2026 updated by: GlaxoSmithKline

A Phase 1, Observer-Blind, Randomized, Controlled Study to Evaluate the Safety and Immunogenicity of an Investigational mRNA Seasonal Flu/COVID-19 Combination Vaccine in Adults

This early-stage study will look at a new mRNA vaccine that combines defenses against both seasonal flu and COVID-19 in terms of its safety and how it builds protection. Healthy adults aged 65 to 85 will receive different doses of this new vaccine, a standard flu vaccine, or COVID-19 vaccine. The study will assess any side effects or health issues, and additional blood samples will be collected at specific times to evaluate how well participants bodies build protection against the flu and COVID-19.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
225

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • California
      • San Diego, California, United States, 92123
        • Recruiting
        • GSK Investigational Site
        • Principal Investigator:
          • Donald Brandon
        • Contact:
        • Contact:
    • Florida
      • Miami, Florida, United States, 33186
        • Recruiting
        • GSK Investigational Site
        • Contact:
        • Contact:
        • Principal Investigator:
          • Rafael A Ubeda

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Participants, who, in the opinion of the investigator, can and will comply with the requirements of the protocol independently or with the assistance of the caregiver.
  2. Informed consent obtained from the participant prior to performance of any study-specific procedure.
  3. A male or female 65 to 85 years of age (YoA) (inclusive) at the time of screening.
  4. Healthy participants or medically stable patients as established by medical history and clinical examination.
  5. Other protocol-defined inclusion criteria may apply.

Exclusion Criteria:

  1. Any clinically significant laboratory abnormality.
  2. History of symptomatic influenza/ SARS-CoV-2 infection confirmed by local health authority-approved testing methods within 180 days (for influenza) or 90 days (SARS-CoV-2 infection) prior to study intervention administration.
  3. History of Guillain-Barré syndrome (GBS) within 6 weeks of receiving any vaccine.
  4. Current or past malignancy, unless completely resolved without clinically significant sequelae (e.g., no evidence of disease following successful treatment of basal cell carcinoma cases are allowed) for >5 years.
  5. Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination (no laboratory testing required).
  6. History of or current suspicion of myocarditis or pericarditis (including following administration of an mRNA vaccine); or idiopathic cardiomyopathy, or presence of any medical condition that increases the risk of myocarditis or pericarditis, including cocaine abuse, cardiomyopathy, endomyocardial fibrosis, hypereosinophilic syndrome, hypersensitivity myocarditis, eosinophilic granulomatosis with polyangiitis and persistent myocardial infection.
  7. History of any reaction or hypersensitivity likely to be exacerbated by any component of the study intervention(s).
  8. Acute or unstable chronic conditions, clinically significant pulmonary, cardiovascular, or renal functional abnormality, as determined by physical examination and/or laboratory screening tests.
  9. History of hypersensitivity or allergic reaction to any previous influenza or COVID-19 vaccine.
  10. History of hypersensitivity or allergic reaction to any previous mRNA vaccine.
  11. Administration of any influenza vaccine within 181 days before the study intervention administration (Day -180 to Day 1) or planned administration within 28 days (Day 29) after the study intervention administration.
  12. Administration of a SARS-CoV-2 antigen-containing vaccine in the period starting 91 days before the study intervention administration (Day -90 to Day 1) or planned administration within 28 days (Day 29) after the study intervention administration.
  13. Administration of any mRNA-based vaccine in the period starting 29 days before the study intervention administration (Day -28 to Day 1) or planned administration within 28 days (Day 29) after the study intervention administration.
  14. Administration of any other vaccine not foreseen by the study protocol in the period starting 29 days (Day -28 to Day 1) before the study intervention administration or planned administration within 28 days (Day 29) after the study intervention administration.
  15. Other protocol-defined exclusion criteria may apply.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Sequential Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: FLU/COVm_Dose Level 1
Participants receive a single intramuscular administration of the investigational mRNA Seasonal Flu/COVID-19 combination vaccine at dose level 1 (Lowest dose).
Biological: Investigational mRNA Seasonal Flu/COVID-19 Combination (Flu/COVm) Vaccine
Flu/COVm Vaccine with multiple dose levels (Dose Level 1, Dose Level 2, and Dose Level 3), will be administered via single intramuscular injection.
Experimental: FLU/COVm_Dose Level 2
Participants receive a single intramuscular administration of the investigational mRNA Seasonal Flu/COVID-19 combination vaccine at dose level 2 (Medium dose).
Biological: Investigational mRNA Seasonal Flu/COVID-19 Combination (Flu/COVm) Vaccine
Flu/COVm Vaccine with multiple dose levels (Dose Level 1, Dose Level 2, and Dose Level 3), will be administered via single intramuscular injection.
Experimental: FLU/COVm_Dose Level 3
Participants receive a single intramuscular administration of the investigational mRNA Seasonal Flu/COVID-19 combination vaccine at dose level 3 (Highest dose).
Biological: Investigational mRNA Seasonal Flu/COVID-19 Combination (Flu/COVm) Vaccine
Flu/COVm Vaccine with multiple dose levels (Dose Level 1, Dose Level 2, and Dose Level 3), will be administered via single intramuscular injection.
Active Comparator: Licensed Seasonal Influenza Vaccine Group
Participants receive a single intramuscular administration of a licensed seasonal Flu vaccine.
Biological: Licensed Seasonal Influenza Vaccine
License Seasonal Influenza Vaccine will be administered as a single intramuscular dose.
Active Comparator: Licensed COVID-19 Vaccine Group
Participants receive a single intramuscular administration of a licensed COVID-19 vaccine.
Biological: Licensed COVID-19 Vaccine
Licensed COVID-19 Vaccine will be administered as a single intramuscular dose.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Number of Participants with an Increase in Toxicity Grade of Laboratory Value Abnormalities Following Administration of the Study Intervention
Time Frame: Day 1 to Day 3
The assessed toxicity grades for laboratory value abnormalities will be defined as follows: Grade 1 = Mild, Grade 2 = Moderate, Grade 3 = Severe, and Grade 4 = Potentially life-threatening.
Day 1 to Day 3
Number of Participants with an Increase in Toxicity Grade of Laboratory Value Abnormalities following Administration of Study Intervention
Time Frame: Day 1 to Day 8
Day 1 to Day 8
Number of Participants with an Increase in Toxicity Grade of Laboratory Value Abnormalities following Administration of Study Intervention
Time Frame: Day 1 to Day 29
Day 1 to Day 29
Number of Participants with Solicited Administration Site Adverse Events (AEs)
Time Frame: Day 1 to Day 7
The solicited administration site AEs considered are pain, redness, swelling and lymphadenopathy.
Day 1 to Day 7
Number of Participants with Solicited Systemic AEs
Time Frame: Day 1 to Day 7
The solicited systemic AEs considered are fever, headache, fatigue, myalgia, arthralgia and chills.
Day 1 to Day 7
Number of Participants with Unsolicited AEs
Time Frame: Day 1 to Day 28
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.
Day 1 to Day 28
Number of Participants with Serious Adverse Events (SAEs)
Time Frame: Day 1 to Day 181
A 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.
Day 1 to Day 181
Number of Participants with Adverse Events of Special Interest (AESIs)
Time Frame: Day 1 to Day 181
The following events are considered as AESI in this study: severe hypersensitivity reactions within 24 hours after study intervention administration, Aminotransferase elevation; myocarditis/pericarditis within 6 weeks after study intervention administration and potential immune-mediated diseases (pIMDs).
Day 1 to Day 181
Number of Participants with Medically Attended Adverse Events (MAAEs)
Time Frame: Day 1 to Day 181
A MAAE is an AE for which the participant received medical attention including any symptom or illness requiring hospitalization, or an emergency room visit, or visit to/by a healthcare professional.
Day 1 to Day 181

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Percentage of Participants with Antigen 1 Seroprotection Rate (SPR)
Time Frame: At Day 1 and Day 29
At Day 1 and Day 29
Geometric Mean Titer (GMT) Of Antigen 1 Titer
Time Frame: At Day 29
At Day 29
Percentage of Participants with Antigen 1 Seroconversion Rate (SCR)
Time Frame: Day 1 to Day 29
Day 1 to Day 29
Geometric Mean Increase (GMI) of Antigen 1 Titer
Time Frame: Day 1 to Day 29
Day 1 to Day 29
GMT Of Antigen 2 Titer
Time Frame: At Day 29
At Day 29
Percentage of Participants with Antigen 2 SCR
Time Frame: Day 1 to Day 29
Day 1 to Day 29
GMI of Antigen 2 Titer
Time Frame: Day 1 to Day 29
Day 1 to Day 29
GMT ratio of serum neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
Time Frame: At Day 29
At Day 29
Percentage of participants with seroresponse of neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
Time Frame: Day 1 to Day 29
Day 1 to Day 29
GMI of neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
Time Frame: Day 1 to Day 29
Day 1 to Day 29

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
GlaxoSmithKline

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 9, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 3, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
June 3, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 6, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 6, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 11, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 27, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 23, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 300768

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

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/About_GSK_Patient_Level_Data_Sharing_Final_13July2023.pdf

IPD Sharing 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.

IPD Sharing 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.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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Sponsors and Collaborators

Medical Conditions

Drug Interventions

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

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