COVID-19Phase 1NCT06680375

A Study of an Investigational Flu Seasonal/SARS-CoV-2 Combination Vaccine in Adults

A Phase 1 study testing Flu Seasonal /SARS-CoV-2 mRNA Dose 1, Flu Seasonal /SARS-CoV-2 mRNA Dose 2 and Flu Seasonal mRNA in people with COVID-19, run by GlaxoSmithKline at 9 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

Who is it for?: Ages 18 to 64 yearsHealthy volunteers can take part
Conditions the study is for: COVID-19
What is being tested?: Flu Seasonal /SARS-CoV-2 mRNA Dose 1, Flu Seasonal /SARS-CoV-2 mRNA Dose 2 and Flu Seasonal mRNA
Type of treatment: Vaccines
Could I receive a placebo?: Yes, some participants may receive a placebo
How many people: 106 participants
Where: 9 sitesUnited States
Study dates: 11 Nov 2024to 9 Jun 2025
Phase: Phase 1
Are there results?: None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 to 64 years
All sexes
Healthy volunteers accepted
Adult

Who may be able to join

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).
Written informed consent obtained from the participant prior to performance of any study-specific procedure.
A male or female 18-64 years of age (YA: 18-64) at the time of the study intervention administration.
Participants must have a body mass index (BMI) >=18 kg/m² and less than equal to (<=) 40 kg/m2.
Healthy participants or medically stable patients as established by medical history, clinical examination and (safety laboratory assessments). Participants with chronic medical conditions with or without specific treatment (e.g., chronic metabolic, cardiac, pulmonary, renal, hepatic, neurologic, and hematologic diseases) are allowed to participate in this study, if considered by the investigator as medically stable. A stable medical condition is defined as disease not requiring significant change in therapy or hospitalization for worsening disease during 3 months before enrolment.
Prior receipt of a COVID-19 vaccine. This may be from a completed primary vaccination series or booster dose(s) of an approved or authorized COVID-19 vaccine. The last COVID-19 vaccination must have been received at least 90 days prior to randomization.

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Women of non-childbearing potential may be enrolled in the study.
Women of childbearing potential may be enrolled in the study if the participant:
has practiced adequate contraception for 4 weeks prior to study intervention administration, and
has a negative pregnancy test on the day of study intervention administration, and has agreed to continue adequate contraception for at least 8 weeks after completion of the study intervention administration.

Who cannot join

Medical conditions
Any clinically significant hematological, biochemical laboratory abnormality.
Participant tested positive for influenza by local health authority-approved testing methods within 180 days prior to Day 1.
A documented history of confirmed SARS-CoV-2 infection within 90 days before study vaccination.
Has had known close contact with anyone who had confirmed influenza or a confirmed SARS-CoV-2 infection within 2 weeks before study vaccination.
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.

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Has any medical disease or psychiatric condition that, in the opinion of the investigator, precludes study participation because it would place the participant at an unacceptable risk of injury, would render them unable to meet the requirements of the protocol, or may interfere with successful completion of the study.
Has a bleeding disorder (e.g., factor deficiency, coagulopathy, or platelet disorder), or prior history of significant bleeding or bruising following IM injections.
Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination (no laboratory testing required).
Any history of an immunosuppressive or immunodeficient condition resulting from disease (e.g., HIV infection or congenital immunodeficiency).
Has a history of hypersensitivity or severe allergic reaction including anaphylaxis, generalized urticaria, angioedema, and other significant reactions to any previous mRNA or non-mRNA vaccine or any component of the study intervention(s) (including polyethylene glycol, egg proteins and aminoglycoside antibiotics)
History of uncontrolled neurological disorders or seizures, including Guillain-Barré syndrome (within 6 weeks of receiving any vaccine) and Bell's Palsy, with the exception of febrile seizures during childhood.
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.
Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the study.
Prior/Concomitant therapy
Use of any investigational or non-registered product (drug, vaccine or invasive medical device) other than the study intervention(s) during the period beginning 28 days before the dose of study intervention(s) (Day -28 to Day 1), or their planned use during the study period.
Administration of any mRNA-based vaccine in the period starting 28 days (Day -28) before study intervention administration.
Administration of any influenza vaccine within 180 days before enrolment or planned administration within 28 days (Day 29) after the study intervention administration.
Administration of a vaccine not foreseen by the study protocol in the period starting 28 days (Day -28) before the study intervention administration or planned administration within 28 days (Day 29) after the study intervention administration.
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.
Up to 3 months prior to the study intervention administration and up to the end of study: For corticosteroids, this will mean prednisone equivalent >=-20 mg/day. Inhaled, intra-articular and topical corticosteroids are allowed. If systemic corticosteroids have been administered short term (<14 days) for treatment of an acute illness, participants should not be enrolled into the study until corticosteroid therapy has been discontinued for at least 28 days before study vaccine administration.
Up to 3 months prior to study intervention administration and up to the end of the study: long-acting immune-modifying drugs including among others immunotherapy (e.g., TNF-inhibitors), monoclonal antibodies, antitumoral medication.
Administration of immunoglobulins and/or any blood products or plasma derivatives within 3 months before study vaccination through end of study.
Prior/Concurrent clinical study experience
Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational intervention.
Other exclusion criteria
Participant is pregnant or has a positive pregnancy test result at Visit 1.
Participant is breastfeeding or will (re)start breastfeeding between Day 1 (study vaccination) to 90 days after vaccination.
Has a history of chronic alcohol consumption and/or drug abuse as deemed by the investigator to render the potential participant unable/unlikely to provide accurate safety reports or comply with study procedures.
Participation of any study personnel or their immediate dependents, family, or household members.
Participants with conditions precluding the assessment of local reactogenicity at the injection site (e.g, tattoos, scarring).
Planned move during the study period that will prohibit participating in the study until study end.

Trial locations and contacts

9 sites in 1 country.

City, postcode or hospital

9 sites in 1 country

United States9 sites

GSK Investigational Site
Anniston, Alabama, 36207
GSK Investigational Site
Hialeah, Florida, 33012
GSK Investigational Site
Lenexa, Kansas, 66219
GSK Investigational Site
Miami, Florida, 33147
GSK Investigational Site
Miami, Florida, 33186
GSK Investigational Site
Omaha, Nebraska, 68134
GSK Investigational Site
Rochester, New York, 14609
GSK Investigational Site
Rolling Hills Estates, California, 90274
GSK Investigational Site
St Louis, Missouri, 63141

Other trials in United States

About this study

Official title: A Phase 1/2, Randomized, Controlled Study to Evaluate the Reactogenicity, Safety, and Immunogenicity of an Investigational Flu Seasonal/SARS-CoV-2 Combination mRNA Vaccine in Adults

This study will evaluate the reactogenicity, safety, and immune response of Flu Seasonal/SARS-CoV-2 mRNA (mRNA Flu/COVID-19) combination vaccine. The flu portion will target multiple strains of the flu virus, while the COVID-19 part will focus on the spike protein of the SARS-CoV-2 virus. Both parts of this vaccine have been tested individually before. This will be the first study to test the combined vaccine in humans in healthy adult participants.

Read the detailed description

Click here to enter text.

Conditions: COVID-19
Being tested: Flu Seasonal /SARS-CoV-2 mRNA Dose 1, Flu Seasonal /SARS-CoV-2 mRNA Dose 2, Flu Seasonal mRNA, SARS-CoV-2 mRNA Dose 1, SARS-CoV-2 mRNA Dose 2
Keywords: Combination vaccine, Flu Seasonal, SARS-CoV-2 mRNA, Healthy younger adults, Healthy older adults, Safety, Reactogenicity, Immunogenicity, First time in humans
Medical subject headings: COVID-19

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Flu Seasonal /SARS-CoV-2 mRNA Dose 1Combination product
A Flu mRNA vaccine composition in combination with Dose 1 of a COVID-19 component will be administered.
Flu Seasonal /SARS-CoV-2 mRNA Dose 2Combination product
A Flu mRNA vaccine composition in combination with Dose 2 of a COVID-19 component will be administered.
Flu Seasonal mRNACombination product
An investigational mRNA Flu Seasonal vaccine will be administered.
SARS-CoV-2 mRNA Dose 1Combination product
Dose 1 of an investigational mRNA COVID-19 vaccine will be administered.
SARS-CoV-2 mRNA Dose 2Combination product
Dose 2 of an investigational mRNA COVID-19 vaccine will be administered.
Licensed Flu SeasonalCombination product
A licensed Flu Seasonal vaccine will be administered.
Licensed COVID-19 mRNACombination product
A licensed mRNA COVID-19 vaccine will be administered.
PlaceboDrug
A placebo will be administered.

Study groups in NCT06680375
Study group	Role	What they receive
mRNA Flu/COVID-19 Dose 1 Group	Experimental	Participants receive one dose of investigational Flu mRNA vaccine composition in combination with a Dose 1 of a COVID-19 component and 1 dose of placebo on Day 1. Receives: Combination Product: Flu Seasonal /SARS-CoV-2 mRNA Dose 1; Drug: Placebo
mRNA Flu/COVID-19 Dose 2 Group	Experimental	Participants receive one dose of a Flu mRNA vaccine composition in combination with a Dose 2 of a COVID-19 component and 1 dose of placebo on Day 1. Receives: Combination Product: Flu Seasonal /SARS-CoV-2 mRNA Dose 2; Drug: Placebo
Flu+COVID-19 Group	Active comparator	Participants receive one dose of a licensed Flu Seasonal vaccine and a licensed mRNA COVID-19 vaccine on Day 1. Receives: Combination Product: Licensed Flu Seasonal; Combination Product: Licensed COVID-19 mRNA
mRNA Flu Group	Active comparator	Participants receive one dose of an investigational mRNA Flu Seasonal vaccine and 1 dose of placebo on Day 1. Receives: Combination Product: Flu Seasonal mRNA; Drug: Placebo
mRNA COVID-19 Dose 1 Group	Active comparator	Participants receive one dose of Dose 1 investigational mRNA COVID-19 vaccine and 1 dose of placebo on Day 1. Receives: Combination Product: SARS-CoV-2 mRNA Dose 1; Drug: Placebo
mRNA COVID-19 Dose 2 Group	Active comparator	Participants receive one Dose 2 investigational mRNA COVID-19 vaccine and 1 dose of placebo on Day 1. Receives: Combination Product: SARS-CoV-2 mRNA Dose 2; Drug: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

Percentage of participants with increase in grading for at least one laboratory value from administration of study intervention
Food and Drug Administration (FDA) toxicity grading scales for biochemistry hematology parameters are evaluated. Grades are defined as follows: Grade 1 - Mild; Grade 2 - Moderate; Grade 3 - Severe; Grade 4 -Potentially life threatening.
Measured: From Day 1 to Day 8
Percentage of participants with solicited administration site adverse events (AEs)
The AEs considered are pain, redness, swelling and lymphadenopathy.
Measured: From Day 1 to Day 7
Percentage of participants with solicited systemic AEs
The 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.
Measured: From Day 1 to Day 7
Percentage 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.
Measured: From Day 1 to Day 28
Percentage of participants with medically attended adverse events (MAAEs)
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.
Measured: From Day 1 to Day 183 (study end)
Percentage of participants with serious adverse events (SAEs)
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.
Measured: From Day 1 to Day 183 (study end)
Percentage of participants with adverse events of special interest (AESIs)
The following events are considered as AESI in this study: severe hypersensitivity reactions within 24 hours after study intervention administration, myocarditis/pericarditis and potential immune-mediated diseases (pIMDs).
Measured: From Day 1 to Day 183 (study end)
Geometric mean titer (GMT) ratio of antigen 1 antibody for investigational mRNA Flu/COVID-19 (pooled dose 1 and dose 2) and mRNA flu vaccines
Measured: At Day 29
GMT ratio of antigen 2 antibody for investigational mRNA Flu/COVID-19 (pooled dose 1 and dose 2) and mRNA flu seasonal vaccines
Measured: At Day 29
GMT ratio of serum neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s) for investigational mRNA Flu/COVID-19 (pooled dose 1 and dose 2) and mRNA COVID-19 vaccines
Measured: At Day 29

Secondary outcomes (13)

GMT ratio of antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines (dose 1 and 2) and Flu vaccines (pooled group) and licensed Flu vaccine co-administered with a licensed mRNA COVID-19 vaccine
Measured: At Day 29
GMT ratio of antigen 2 antibody for the investigational mRNA Flu/COVID-19 vaccines (dose 1 and 2) and Flu vaccines (pooled group) and licensed Flu vaccine co-administered with a licensed mRNA COVID-19 vaccine
Measured: At Day 29
GMT ratio of serum neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
GMT ratio of serum neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s) will be evaluated for the investigational mRNA Flu/COVID-19 vaccines and COVID-19 with the same dose (pooled group) and licensed mRNA COVID-19 vaccine co-administered with a licensed Flu Seasonal vaccine.
Measured: At Day 29
GMTs of antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Measured: At Day 92 and Day 183 (Study end)
Geometric mean increase (GMI) in antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
GMI is defined as the geometric mean of the ratios of the post-vaccination titer over the Day 1 titer.
Measured: From Day 1 to Day 29, from Day 1 to Day 92 and from Day 1 to Day 183 (study end)
Seroconversion rate (SCR) of antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Measured: From Day 1 to Day 29, from Day 1 to Day 92 and from Day 1 to Day 183 (study end)
Seroprotection rate (SPR) of antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Measured: At Day 1, Day 29, Day 92, and Day 183 (study end)
GMTs of antigen 2 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Measured: At Day 92 and Day 183 (study end)
GMI in antigen 2 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
GMI is defined as the geometric mean of the ratios of the post-vaccination titer over the Day 1 titer.
Measured: From Day 1 to Day 29, from Day 1 to Day 92 and from Day 1 to Day 183 (study end)
SCR of antigen 2 antibody in for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Measured: From Day 1 to Day 29, from Day 1 to Day 92 and from Day 1 to Day 183 (study end)
GMTs of serum neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
GMTs of serum neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s) will be evaluated for the investigational mRNA Flu/COVID-19 vaccines, mRNA COVID-19 vaccine and the licensed mRNA COVID-19 vaccine co-administered with a licensed Flu Seasonal vaccine
Measured: At Day 92, and Day 183 (study end)
GMI of neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
GMI is defined as the geometric mean of the ratios of the post-vaccination titer over the Day 1 titer. GMI of neutralization titers will be evaluated for the investigational mRNA Flu/COVID-19 vaccines, mRNA COVID-19 vaccine and the licensed mRNA COVID-19 vaccine co-administered with a licensed Flu Seasonal vaccine.
Measured: At Day 29, Day 92, and Day 183 (study end)
Percentage of participants with seroresponse of neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
Seroresponse of neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s) will be evaluated for the investigational mRNA Flu/COVID-19 vaccines, mRNA COVID-19 vaccine and the licensed mRNA COVID-19 vaccine co-administered with a licensed Flu Seasonal vaccine.
Measured: At Day 29, Day 92, and Day 183 (study end)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

11 Nov 20249 Jun 2025

First posted8 Nov 2024
Study start11 Nov 2024
Primary completion9 Jun 2025
Study completion9 Jun 2025

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Other trials for COVID-19Studies of the same condition, open and under way.
More trials run by GlaxoSmithKlineThe sponsor's other registered studies.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 1
Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind
Who is masked: Participant, Investigator, Outcomes assessor
Enrolment: 106 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06680375
Sponsor's protocol ID: 221542
Status last verified: Sep 2025
First submitted: 6 Nov 2024
Last updated: 11 Sep 2025
Results posted: No
Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: 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/About\_GSK\_Patient\_Level\_Data\_Sharing\_Final\_13July2023.pdf

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

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Study at a glance

From the registry record, last updated by the sponsor on 11 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Phase 1/2, Randomized, Controlled Study to Evaluate the Reactogenicity, Safety, and Immunogenicity of an Investigational Flu Seasonal/SARS-CoV-2 Combination mRNA Vaccine in Adults
ClinicalTrials.gov ID: NCT06680375
Acronym / sponsor ID: 221542
Conditions: COVID-19
Keywords: Combination vaccine, Flu Seasonal, SARS-CoV-2 mRNA, Healthy younger adults, Healthy older adults, Safety, Reactogenicity, Immunogenicity
Phase: Phase 1
Study type: Interventional
Recruitment status: Completed
Enrolment: 106 participants (actual)
Lead sponsor: GlaxoSmithKlineIndustry (pharma, biotech, devices)
Study start: 11 Nov 2024 (actual)
Primary completion: 9 Jun 2025 (actual)
Study completion: 9 Jun 2025 (actual)
First posted: 8 Nov 2024 (actual)
Results: Not posted in the source record

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

Click here to enter text.

Study design

Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind (participant, investigator, outcomes assessor)
Number of arms: 6

Arm	Type	Receives
mRNA Flu/COVID-19 Dose 1 Group	Experimental	Combination Product: Flu Seasonal /SARS-CoV-2 mRNA Dose 1, Drug: PlaceboParticipants receive one dose of investigational Flu mRNA vaccine composition in combination with a Dose 1 of a COVID-19 component and 1 dose of placebo on Day 1.
mRNA Flu/COVID-19 Dose 2 Group	Experimental	Combination Product: Flu Seasonal /SARS-CoV-2 mRNA Dose 2, Drug: PlaceboParticipants receive one dose of a Flu mRNA vaccine composition in combination with a Dose 2 of a COVID-19 component and 1 dose of placebo on Day 1.
Flu+COVID-19 Group	Active comparator	Combination Product: Licensed Flu Seasonal, Combination Product: Licensed COVID-19 mRNAParticipants receive one dose of a licensed Flu Seasonal vaccine and a licensed mRNA COVID-19 vaccine on Day 1.
mRNA Flu Group	Active comparator	Combination Product: Flu Seasonal mRNA, Drug: PlaceboParticipants receive one dose of an investigational mRNA Flu Seasonal vaccine and 1 dose of placebo on Day 1.
mRNA COVID-19 Dose 1 Group	Active comparator	Combination Product: SARS-CoV-2 mRNA Dose 1, Drug: PlaceboParticipants receive one dose of Dose 1 investigational mRNA COVID-19 vaccine and 1 dose of placebo on Day 1.
mRNA COVID-19 Dose 2 Group	Active comparator	Combination Product: SARS-CoV-2 mRNA Dose 2, Drug: PlaceboParticipants receive one Dose 2 investigational mRNA COVID-19 vaccine and 1 dose of placebo on Day 1.

Who may qualify

Ages: 18 to 64 years
Sex: All
Healthy volunteers: Accepted
Age groups: Adult

Key inclusion criteria (10 listed)

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).
Written informed consent obtained from the participant prior to performance of any study-specific procedure.
A male or female 18-64 years of age (YA: 18-64) at the time of the study intervention administration.
Participants must have a body mass index (BMI) >=18 kg/m² and less than equal to (<=) 40 kg/m2.
Healthy participants or medically stable patients as established by medical history, clinical examination and (safety laboratory assessments). Participants with chronic medical conditions with or without specific treatment (e.g., chronic metabolic, cardiac, pulmonary, renal, hepatic, neurologic, and hematologic diseases) are allowed to participate in this study, if considered by the investigator as medically stable. A stable medical condition is defined as disease not requiring significant change in therapy or hospitalization for worsening disease during 3 months before enrolment.

Key exclusion criteria (32 listed)

Medical conditions
Any clinically significant hematological, biochemical laboratory abnormality.
Participant tested positive for influenza by local health authority-approved testing methods within 180 days prior to Day 1.
A documented history of confirmed SARS-CoV-2 infection within 90 days before study vaccination.
Has had known close contact with anyone who had confirmed influenza or a confirmed SARS-CoV-2 infection within 2 weeks before study vaccination.

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
Flu Seasonal /SARS-CoV-2 mRNA Dose 1A Flu mRNA vaccine composition in combination with Dose 1 of a COVID-19 component will be administered.	Combination product	mRNA Flu/COVID-19 Dose 1 Group
Flu Seasonal /SARS-CoV-2 mRNA Dose 2A Flu mRNA vaccine composition in combination with Dose 2 of a COVID-19 component will be administered.	Combination product	mRNA Flu/COVID-19 Dose 2 Group
Flu Seasonal mRNAAn investigational mRNA Flu Seasonal vaccine will be administered.	Combination product	mRNA Flu Group
SARS-CoV-2 mRNA Dose 1Dose 1 of an investigational mRNA COVID-19 vaccine will be administered.	Combination product	mRNA COVID-19 Dose 1 Group
SARS-CoV-2 mRNA Dose 2Dose 2 of an investigational mRNA COVID-19 vaccine will be administered.	Combination product	mRNA COVID-19 Dose 2 Group
Licensed Flu SeasonalA licensed Flu Seasonal vaccine will be administered.	Combination product	Flu+COVID-19 Group
Licensed COVID-19 mRNAA licensed mRNA COVID-19 vaccine will be administered.	Combination product	Flu+COVID-19 Group
PlaceboA placebo will be administered.	Drug	mRNA COVID-19 Dose 1 Group, mRNA COVID-19 Dose 2 Group, mRNA Flu Group, mRNA Flu/COVID-19 Dose 1 Group, mRNA Flu/COVID-19 Dose 2 Group

Primary outcome

Percentage of participants with increase in grading for at least one laboratory value from administration of study intervention
Time frame: From Day 1 to Day 8
Food and Drug Administration (FDA) toxicity grading scales for biochemistry hematology parameters are evaluated. Grades are defined as follows: Grade 1 - Mild; Grade 2 - Moderate; Grade 3 - Severe; Grade 4 -Potentially life threatening.
Percentage of participants with solicited administration site adverse events (AEs)
Time frame: From Day 1 to Day 7
The AEs considered are pain, redness, swelling and lymphadenopathy.
Percentage of participants with solicited systemic AEs
Time frame: From Day 1 to Day 7
The 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.
Percentage of participants with unsolicited AEs
Time frame: From 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.
Percentage of participants with medically attended adverse events (MAAEs)
Time frame: From Day 1 to Day 183 (study end)
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.
Percentage of participants with serious adverse events (SAEs)
Time frame: From Day 1 to Day 183 (study end)
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.
Percentage of participants with adverse events of special interest (AESIs)
Time frame: From Day 1 to Day 183 (study end)
The following events are considered as AESI in this study: severe hypersensitivity reactions within 24 hours after study intervention administration, myocarditis/pericarditis and potential immune-mediated diseases (pIMDs).
Geometric mean titer (GMT) ratio of antigen 1 antibody for investigational mRNA Flu/COVID-19 (pooled dose 1 and dose 2) and mRNA flu vaccines
Time frame: At Day 29
GMT ratio of antigen 2 antibody for investigational mRNA Flu/COVID-19 (pooled dose 1 and dose 2) and mRNA flu seasonal vaccines
Time frame: At Day 29
GMT ratio of serum neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s) for investigational mRNA Flu/COVID-19 (pooled dose 1 and dose 2) and mRNA COVID-19 vaccines
Time frame: At Day 29

13 secondary outcomes

GMT ratio of antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines (dose 1 and 2) and Flu vaccines (pooled group) and licensed Flu vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: At Day 29
GMT ratio of antigen 2 antibody for the investigational mRNA Flu/COVID-19 vaccines (dose 1 and 2) and Flu vaccines (pooled group) and licensed Flu vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: At 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
GMTs of antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: At Day 92 and Day 183 (Study end)
Geometric mean increase (GMI) in antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: From Day 1 to Day 29, from Day 1 to Day 92 and from Day 1 to Day 183 (study end)
Seroconversion rate (SCR) of antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: From Day 1 to Day 29, from Day 1 to Day 92 and from Day 1 to Day 183 (study end)
Seroprotection rate (SPR) of antigen 1 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: At Day 1, Day 29, Day 92, and Day 183 (study end)
GMTs of antigen 2 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: At Day 92 and Day 183 (study end)
GMI in antigen 2 antibody for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: From Day 1 to Day 29, from Day 1 to Day 92 and from Day 1 to Day 183 (study end)
SCR of antigen 2 antibody in for the investigational mRNA Flu/COVID-19 vaccines, mRNA Flu Seasonal vaccine and the licensed Flu Seasonal vaccine co-administered with a licensed mRNA COVID-19 vaccine
Time frame: From Day 1 to Day 29, from Day 1 to Day 92 and from Day 1 to Day 183 (study end)
GMTs of serum neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
Time frame: At Day 92, and Day 183 (study end)
GMI of neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
Time frame: At Day 29, Day 92, and Day 183 (study end)
Percentage of participants with seroresponse of neutralization titers against pseudovirus bearing spike from SARS-CoV-2 vaccine matched variant(s)
Time frame: At Day 29, Day 92, and Day 183 (study end)

Results and safety

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 11 Sep 2025.
Individual participant dataSharing planned: 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/About_GSK_Patient_Level_Data_Sharing_Final_13July2023.pdf

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

The record lists no contact. Use the official record to reach the sponsor.

9 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing Flu Seasonal /SARS-CoV-2 mRNA Dose 1, Flu Seasonal /SARS-CoV-2 mRNA Dose 2 and Flu Seasonal mRNA in people with COVID-19, run by GlaxoSmithKline at 9 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 10 inclusion and 32 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 11 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 9 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Percentage of participants with increase in grading for at least one laboratory value from administration of study intervention (time frame: From Day 1 to Day 8). The study lists 10 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06680375.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Sep 2025.