A Study to Find the Dose and Assess the Immune Response and Safety of a Vaccine Against Influenza in Healthy Younger and Older Adults

A Phase 2a Randomized, Observer-blind, Dose-finding Study to Evaluate the Immunogenicity and Safety of mRNA-based Multivalent Seasonal Influenza Vaccine Candidates in Adults 18 Years of Age and Older

The purpose of this study is to assess the safety and immune response of GlaxoSmithKlines (GSK) messenger RNA (mRNA)-based multivalent vaccine (GSK4382276A) candidate against influenza, administered in healthy younger adults (YA) and older adults (OA).

Study Overview

• Status: Completed
• Conditions: Influenza, Human
• Intervention / Treatment: Biological: F2G22B/DL001Z; Biological: F2H23D/DL001Z-NH; Biological: F2H23B/DL001Z-NH; Biological: F2H23H/DL001Z; Combination product: FDQ23A-NH (Flu D-QIV); Biological: GSK5800544A; Combination product: Flu D-TIV; Biological: F2H23A/DL001Z-NH; Biological: F2H23G/DL001Z; Combination product: Fluzone HD Quadrivalent; Combination product: Fluzone HD

• Study Type: Interventional
• Enrollment (Actual): 845
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Florida
    • Hialeah, Florida, United States, 33012
      • GSK Investigational Site
    • Miami, Florida, United States, 33186
      • GSK Investigational Site
    • Miami, Florida, United States, 33147
      • GSK Investigational Site
  • Illinois
    • Chicago, Illinois, United States, 60640
      • GSK Investigational Site
  • Indiana
    • Valparaiso, Indiana, United States, 46383
      • GSK Investigational Site
  • Kansas
    • El Dorado, Kansas, United States, 67042
      • GSK Investigational Site
    • Lenexa, Kansas, United States, 66219
      • GSK Investigational Site
    • Newton, Kansas, United States, 67114
      • GSK Investigational Site
    • Wichita, Kansas, United States, 67207
      • GSK Investigational Site
  • Kentucky
    • Lexington, Kentucky, United States, 40509
      • GSK Investigational Site
  • New York
    • Rochester, New York, United States, 14609
      • GSK Investigational Site
  • North Carolina
    • Greensboro, North Carolina, United States, 27408
      • GSK Investigational Site
  • Tennessee
    • Knoxville, Tennessee, United States, 37909
      • GSK Investigational Site
  • Texas
    • Austin, Texas, United States, 78705
      • GSK Investigational Site
    • Fort Worth, Texas, United States, 76135
      • GSK Investigational Site
    • Tomball, Texas, United States, 77375
      • GSK Investigational Site
  • Virginia
    • Newport News, Virginia, United States, 23606
      • GSK Investigational Site
    • Norfolk, Virginia, United States, 23502
      • GSK Investigational Site

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. A male or female between and including 18 and 85 years of age (YAs: 18-64; OAs: 65-85) at the time of the study intervention administration.
2. Healthy participants or medically stable patients as established by medical history and clinical examination. 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.
3. Body mass index (BMI) >=18 Kilograms per meter square (kg/m²) and less than or equal to (<=) 35kg/m2.
4. Participants who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g., completion of the diary cards, return for follow-up visits), independently or with the assistance of a caregiver.
5. Written informed consent obtained from the participant prior to performance of any study-specific procedure.
6. Female participants of non-childbearing potential may be enrolled in the clinical study.

7. Female participants of childbearing potential may be enrolled in the clinical study, if the participant:

   • Has practiced adequate contraception for 1 month prior to the study intervention administration, and
   • Has a negative pregnancy test within 24 hours prior to the study intervention administration, and
   • Has agreed to continue adequate contraception for at least 1 month after study intervention administration.

Exclusion Criteria:

1. Participant tested positive for influenza by local health authority-approved testing methods within 180 days prior to Day 1.
2. Current or past malignancy, unless completely resolved without sequelae for greater than (>) 5 years before the study intervention administration (excluding effectively treated basal cell skin cancer).
3. Any confirmed or suspected immunosuppressive or immunodeficient condition based on medical history and physical examination (no laboratory testing required). HIV-infected individuals may be enrolled if they have been stable on antiretroviral therapy for the past 6 consecutive months, i.e., their treatment has not been modified, their cluster of differentiation 4 (CD4) cell count is >= 200/ cubic millimeter (mm³) and their viral load has been undetectable (i.e., HIV-RNA lesser than (<) 50 copies/milliliter [mL]) (based on medical records, no laboratory testing required).
4. Participants with a history of, or current suspicion of myocarditis, pericarditis, or idiopathic cardiomyopathy (including a history of myocarditis or pericarditis following vaccination with an mRNA COVID-19 vaccine), or presence of any medical condition that increases risk of myocarditis or pericarditis, including cocaine abuse, cardiomyopathy, endomyocardial fibrosis, hypereosinophilic syndrome, hypersensitivity myocarditis, eosinophilic granulomatosis with polyangiitis and persistent myocardial infection will be excluded from the study.
5. History of any reaction or hypersensitivity likely to be exacerbated by any component of the study intervention (including polyethylene glycol, egg proteins and aminoglycoside antibiotics).
6. Hypersensitivity to latex.
7. Recurrent history or uncontrolled neurological disorders or seizures, including Guillain-Barré syndrome and Bell's palsy, with the exception of febrile seizures during childhood.
8. Any history of dementia or any medical condition that moderately or severely impairs cognition.
9. Any condition that in the judgment of the investigator would make intramuscular injection unsafe.
10. Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the clinical study.
11. Administration of an influenza vaccine within 180 days before enrollment or planned administration prior to Visit 2 (Day 29) after the study intervention administration.
12. Previous vaccination with a mRNA influenza vaccine.

13. Administration of a vaccine not foreseen by the study protocol in the period starting 30 days (Day -30) before the study intervention administration, or planned administration within 28 days (Visit 2 [Day 29]) after the study intervention administration*.

    • If emergency mass vaccination for an unforeseen public health threat (e.g., a pandemic) is recommended and/or organized by public health authorities outside the routine immunization program, the time period described above can be reduced, provided it is used according to the local governmental recommendations and sponsor is notified.
14. Use of any investigational or non-registered product (drug, vaccine or invasive medical device) other than the study intervention during the period beginning 30 days before the study intervention administration, or their planned use during the study period.
15. Administration of immunoglobulins and/or any blood products or plasma derivatives during the period starting 90 days before the study intervention administration or planned administration during the study period.

16. 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:

    For corticosteroids, this will mean prednisone equivalent >=20 mg/day. Inhaled, intraarticular and topical steroids are allowed.

    • Up to 3 months prior to study intervention administration: long-acting immune-modifying drugs including among others immunotherapy (e.g., TNF-inhibitors), monoclonal antibodies, antitumoral medication.
17. 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 (drug/invasive medical device).
18. Pregnant or lactating female participant.
19. Bedridden participants.
20. Female participant planning to become pregnant or planning to discontinue contraceptive precautions within the 1-month post-dosing period.
21. History of chronic alcohol consumption and/or drug abuse in the past 5 years as deemed by the investigator to render the potential participant unable/unlikely to provide accurate safety reports or comply with study procedures.
22. Any study personnel or their immediate dependents, family, or household members.
23. Participants with extensive tattoos covering deltoid region on both arms that would preclude the assessment of local reactogenicity.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

14

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Part 1 YA: Flu mRNA_1_Younger Adults (YA); YA participants received a single dose of Flu mRNA study intervention F2G22B/DL001Z administered at Day 1.	Biological: F2G22B/DL001Z; Study intervention was administered intramuscularly at Day 1.
Experimental: Part 1 YA: Flu mRNA_2_YA; YA participants received a single dose of Flu mRNA study intervention F2H23D/DL001Z-NH administered at Day 1.	Biological: F2H23D/DL001Z-NH; Study intervention was administered intramuscularly at Day 1.
Experimental: Part 1 YA: Flu mRNA_3_YA; YA participants received a single dose of Flu mRNA study intervention F2H23B/DL001Z-NH administered at Day 1.	Biological: F2H23B/DL001Z-NH; Study intervention was administered intramuscularly at Day 1.
Experimental: Part 1 YA: Flu mRNA_4_YA; YA participants received a single dose of Flu mRNA study intervention F2H23H/DL001Z administered at Day 1.	Biological: F2H23H/DL001Z; Study intervention was administered intramuscularly at Day 1.
Active Comparator: Part 1 YA: Comparator_1_YA; YA participants received a single dose of Comparator 1 [FDQ23A-NH (Flu D-QIV)] administered at Day 1.	Combination product: FDQ23A-NH (Flu D-QIV); Control Vaccine was administered intramuscularly at Day 1.
Experimental: Part 2 YA: Flu mRNA_9_YA; YA participants received a single dose of Flu mRNA study intervention GSK5800544A administered at Day 1.	Biological: GSK5800544A; Study intervention was administered intramuscularly at Day 1.
Active Comparator: Part 2 YA: Comparator_2_YA; YA participants received a single dose of Comparator 2 (Flu D-TIV) administered at Day 1.	Combination product: Flu D-TIV; Control Vaccine was administered intramuscularly at Day 1.
Experimental: Part 1 OA: Flu mRNA_5_Older Adults (OA); OA participants received a single dose of Flu mRNA study intervention F2H23B/DL001Z-NH administered at Day 1.	Biological: F2H23B/DL001Z-NH; Study intervention was administered intramuscularly at Day 1.
Experimental: Part 1 OA: Flu mRNA_6_OA; OA participants received a single dose of Flu mRNA study intervention F2H23A/DL001Z-NH administered at Day 1.	Biological: F2H23A/DL001Z-NH; Study intervention was administered intramuscularly at Day 1.
Experimental: Part 1 OA: Flu mRNA_7_OA; OA participants received a single dose of Flu mRNA study intervention F2H23H/DL001Z administered at Day 1.	Biological: F2H23H/DL001Z; Study intervention was administered intramuscularly at Day 1.
Experimental: Part 1 OA: Flu mRNA_8_OA; OA participants received a single dose of Flu mRNA study intervention F2H23G/DL001Z administered at Day 1.	Biological: F2H23G/DL001Z; Study intervention was administered intramuscularly at Day 1.
Active Comparator: Part 1 OA: Comparator_1_OA; OA participants received a single dose of Comparator 1 (Fluzone HD Quadrivalent) administered at Day 1.	Combination product: Fluzone HD Quadrivalent; Control vaccine was administered intramuscularly at Day 1.
Experimental: Part 2 OA: Flu mRNA_10_OA; OA participants received a single dose of Flu mRNA study intervention GSK5800544A administered at Day 1.	Biological: GSK5800544A; Study intervention was administered intramuscularly at Day 1.
Active Comparator: Part 2 OA: Comparator_2_OA; OA participants received a single dose of Comparator 2 (Fluzone HD) administered at Day 1.	Combination product: Fluzone HD; Control vaccine was administered intramuscularly at Day 1.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Part 1 YA: Geometric Mean Titer (GMT) of Antigen 1 Antibody Titer	Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 29
Part 2 YA: GMT of Antigen 1 Antibody Titer	Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 29
Part 1 OA: GMT of Antigen 1 Antibody Titer	Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 29
Part 2 OA: GMT of Antigen 1 Antibody Titer	Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 29
Part 1 YA: Geometric Mean Increase (GMI) of Antigen 1 Antibody Titers	GMI is defined as the geometric mean of the ratios of the post dosing titer over the Day 1 titer. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	From Day 1 (baseline) to Day 29
Part 2 YA: GMI of Antigen 1 Antibody Titers	GMI is defined as the geometric mean of the ratios of the post dosing titer over the Day 1 titer. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	From Day 1 (baseline) to Day 29
Part 1 OA: GMI of Antigen 1 Antibody Titers	GMI is defined as the geometric mean of the ratios of the post dosing titer over the Day 1 titer. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	From Day 1 (baseline) to Day 29
Part 2 OA: GMI of Antigen 1 Antibody Titers	GMI is defined as the geometric mean of the ratios of the post dosing titer over the Day 1 titer. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	From Day 1 (baseline) to Day 29
Part 1 YA: Percentage of Participants With Antigen 1 Antibody Seroconversion Rate (SCR)	SCR is defined as the percentage of dosed participants who have either an anti-vaccine antibody pre-dose titer < 1:10 and a post-dose anti-vaccine antibody titer >= 1:40 or a pre-dose anti-vaccine antibody titer >= 1:10 and at least a 4-fold increase in post-dose anti-vaccine antibody titer. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	From Day 1 (baseline) to Day 29
Part 2 YA: Percentage of Participants With Antigen 1 Antibody SCR	SCR is defined as the percentage of dosed participants who have either an anti-vaccine antibody pre-dose titer < 1:10 and a post-dose anti-vaccine antibody titer >= 1:40 or a pre-dose anti-vaccine antibody titer >= 1:10 and at least a 4-fold increase in post-dose anti-vaccine antibody titer. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	From Day 1 (baseline) to Day 29
Part 1 OA: Percentage of Participants With Antigen 1 Antibody SCR	SCR is defined as the percentage of dosed participants who have either an anti-vaccine antibody pre-dose titer < 1:10 and a post-dose anti-vaccine antibody titer >= 1:40 or a pre-dose anti-vaccine antibody titer >= 1:10 and at least a 4-fold increase in post-dose anti-vaccine antibody titer. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	From Day 1 (baseline) to Day 29
Part 2 OA: Percentage of Participants With Antigen 1 Antibody SCR	SCR is defined as the percentage of dosed participants who have either an anti-vaccine antibody pre-dose titer < 1:10 and a post-dose anti-vaccine antibody titer >= 1:40 or a pre-dose anti-vaccine antibody titer >= 1:10 and at least a 4-fold increase in post-dose anti-vaccine antibody titer. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	From Day 1 (baseline) to Day 29
Part 1 YA: Percentage of Participants With Antigen 1 Antibody Seroprotection Rate (SPR)	SPR is defined as the percentage of dosed participants with a anti-vaccine antibody titer >= 1:40. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 1
Part 2 YA: Percentage of Participants With Antigen 1 Antibody SPR	SPR is defined as the percentage of dosed participants with a anti-vaccine antibody titer >= 1:40. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 1
Part 1 OA: Percentage of Participants With Antigen 1 Antibody SPR	SPR is defined as the percentage of dosed participants with a anti-vaccine antibody titer >= 1:40. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 1
Part 2 OA: Percentage of Participants With Antigen 1 Antibody SPR	SPR is defined as the percentage of dosed participants with a anti-vaccine antibody titer >= 1:40. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 1
Part 1 YA: Percentage of Participants With Antigen 1 Antibody SPR	SPR is defined as the percentage of dosed participants with a anti-vaccine antibody titer >= 1:40. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 29
Part 2 YA: Percentage of Participants With Antigen 1 Antibody SPR	SPR is defined as the percentage of dosed participants with a anti-vaccine antibody titer >= 1:40. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 29
Part 1 OA: Percentage of Participants With Antigen 1 Antibody SPR	SPR is defined as the percentage of dosed participants with a anti-vaccine antibody titer >= 1:40. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 29
Part 2 OA: Percentage of Participants With Antigen 1 Antibody SPR	SPR is defined as the percentage of dosed participants with a anti-vaccine antibody titer >= 1:40. Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.	At Day 29

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Part 1 YA: GMT of Antigen 2 Antibody Titer		At Day 29
Part 2 YA: GMT of Antigen 2 Antibody Titer		At Day 29
Part 1 OA: GMT of Antigen 2 Antibody Titer		At Day 29
Part 2 OA: GMT of Antigen 2 Antibody Titer		At Day 29
Part 1 YA: GMI of Antigen 2 Antibody Titer		From Day 1 (baseline) to Day 29
Part 2 YA: GMI of Antigen 2 Antibody Titer		From Day 1 (baseline) to Day 29
Part 1 OA: GMI of Antigen 2 Antibody Titer		From Day 1 (baseline) to Day 29
Part 2 OA: GMI of Antigen 2 Antibody Titer		From Day 1 (baseline) to Day 29
Part 1 YA: Percentage of Participants With Antigen 2 Antibody SCR		From Day 1 (baseline) to Day 29
Part 2 YA: Percentage of Participants With Antigen 2 Antibody SCR		From Day 1 (baseline) to Day 29
Part 1 OA: Percentage of Participants With Antigen 2 Antibody SCR		From Day 1 (baseline) to Day 29
Part 2 OA: Percentage of Participants With Antigen 2 Antibody SCR		From Day 1 (baseline) to Day 29
Part 1 YA: Number of Participants Reporting Any Solicited Administration Site Adverse Events (AEs)	Assessed solicited administration site events included pain, redness (erythema), swelling, lymphadenopathy (defined as localized axillary, cervical or supraclavicular swelling or tenderness ipsilateral to the injection arm). Any = occurrence of the event regardless of intensity grade.	Day 1 to Day 7
Part 2 YA: Number of Participants Reporting Any Solicited Administration Site AEs	Assessed solicited administration site events included pain, redness (Erythema), swelling, lymphadenopathy (defined as localized axillary, cervical or supraclavicular swelling or tenderness ipsilateral to the injection arm). Any = occurrence of the event regardless of intensity grade.	Day 1 to Day 7
Part 1 OA: Number of Participants Reporting Any Solicited Administration Site AEs	Assessed solicited administration site events included pain, redness (Erythema), swelling, lymphadenopathy (defined as localized axillary, cervical or supraclavicular swelling or tenderness ipsilateral to the injection arm). Any = occurrence of the event regardless of intensity grade.	Day 1 to Day 7
Part 2 OA: Number of Participants Reporting Any Solicited Administration Site AEs	Assessed solicited administration site events included pain, redness (Erythema), swelling, lymphadenopathy (defined as localized axillary, cervical or supraclavicular swelling or tenderness ipsilateral to the injection arm). Any = occurrence of the event regardless of intensity grade.	Day 1 to Day 7
Part 1 YA: Number of Participants Reporting Any Solicited Systemic AEs	Assessed solicited systemic events included fever (pyrexia) which is defined as axillary temperature greater than or equal to (>=) 38.0°C/100.4°F, chills, headache, fatigue (tiredness), myalgia (muscle joint), and arthralgia (joint pain). Any = occurrence of the event regardless of intensity grade.	Day 1 to Day 7
Part 2 YA: Number of Participants Reporting Any Solicited Systemic AEs	Assessed solicited systemic events included fever (pyrexia) which is defined as axillary temperature >= 38.0°C/100.4°F, chills, headache, fatigue (tiredness), myalgia (muscle joint), and arthralgia (joint pain). Any = occurrence of the event regardless of intensity grade.	Day 1 to Day 7
Part 1 OA: Number of Participants Reporting Any Solicited Systemic AEs	Assessed solicited systemic events included fever (pyrexia) which is defined as axillary temperature >= 38.0°C/100.4°F, chills, headache, fatigue (tiredness), myalgia (muscle joint), and arthralgia (joint pain). Any = occurrence of the event regardless of intensity grade.	Day 1 to Day 7
Part 2 OA: Number of Participants Reporting Any Solicited Systemic AEs	Assessed solicited systemic events included fever (pyrexia) which is defined as axillary temperature >= 38.0°C/100.4°F, chills, headache, fatigue (tiredness), myalgia (muscle joint), and arthralgia (joint pain). Any = occurrence of the event regardless of intensity grade.	Day 1 to Day 7
Part 1 YA: Number of Participants Reporting Any Unsolicited AEs	An unsolicited AE is defined as 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. Unsolicited AEs include both serious and non-serious AEs. Any = occurrence the event regardless of intensity grade.	Day 1 to Day 28
Part 2 YA: Number of Participants Reporting Any Unsolicited AEs	An unsolicited AE is defined as 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. Unsolicited AEs include both serious and non-serious AEs. Any = occurrence the event regardless of intensity grade.	Day 1 to Day 28
Part 1 OA: Number of Participants Reporting Any Unsolicited AEs	An unsolicited AE is defined as 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. Unsolicited AEs include both serious and non-serious AEs. Any = occurrence the event regardless of intensity grade.	Day 1 to Day 28
Part 2 OA: Number of Participants Reporting Any Unsolicited AEs	An unsolicited AE is defined as 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. Unsolicited AEs include both serious and non-serious AEs. Any = occurrence the event regardless of intensity grade.	Day 1 to Day 28
Part 1 YA: Number of Participants Reporting Serious Adverse Events (SAEs)	An SAE is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect in the offspring of a study participant, is an abnormal pregnancy outcome, or is a suspected transmission of any infectious agent via an authorized medicinal product. Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 2 YA: Number of Participants Reporting SAEs	An SAE is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect in the offspring of a study participant, is an abnormal pregnancy outcome, or is a suspected transmission of any infectious agent via an authorized medicinal product. Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 1 OA: Number of Participants Reporting SAEs	An SAE is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect in the offspring of a study participant, is an abnormal pregnancy outcome, or is a suspected transmission of any infectious agent via an authorized medicinal product. Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 2 OA: Number of Participants Reporting SAEs	An SAE is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect in the offspring of a study participant, is an abnormal pregnancy outcome, or is a suspected transmission of any infectious agent via an authorized medicinal product. Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 1 YA: Number of Participants Reporting AEs of Special Interest (AESIs)	The following events were considered as AESI in this study: severe hypersensitivity reactions within 24 hours after study intervention administration, myocarditis/pericarditis and potential immune-mediated diseases (pIMDs). Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 2 YA: Number of Participants Reporting AESIs	The following events were considered as AESI in this study: severe hypersensitivity reactions within 24 hours after study intervention administration, myocarditis/pericarditis and potential immune-mediated diseases (pIMDs). Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 1 OA: Number of Participants Reporting AESIs	The following events were considered as AESI in this study: severe hypersensitivity reactions within 24 hours after study intervention administration, myocarditis/pericarditis and potential immune-mediated diseases (pIMDs). Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 2 OA: Number of Participants Reporting AESIs	The following events were considered as AESI in this study: severe hypersensitivity reactions within 24 hours after study intervention administration, myocarditis/pericarditis and potential immune-mediated diseases (pIMDs). Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 1 YA: Number of Participants Reporting Medically Attended Adverse Events (MAAEs)	MAE is defined as an AE that results in an unscheduled visit to a medical professional (e.g., physician's office visits, emergency room visits or hospitalization). Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 2 YA: Number of Participants Reporting MAAEs	MAE is defined as an AE that results in an unscheduled visit to a medical professional (e.g., physician's office visits, emergency room visits or hospitalization). Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 1 OA: Number of Participants Reporting MAAEs	MAE is defined as an AE that results in an unscheduled visit to a medical professional (e.g., physician's office visits, emergency room visits or hospitalization). Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183
Part 2 OA: Number of Participants Reporting MAAEs	MAE is defined as an AE that results in an unscheduled visit to a medical professional (e.g., physician's office visits, emergency room visits or hospitalization). Any = occurrence the event regardless of intensity grade.	Day 1 to Day 183

Collaborators and Investigators

• Sponsor: GlaxoSmithKline

Study record dates

Study Major Dates

• Study Start (Actual): May 23, 2024
• Primary Completion (Actual): December 27, 2024
• Study Completion (Actual): June 4, 2025

Study Registration Dates

• First Submitted: May 22, 2024
• First Submitted That Met QC Criteria: May 22, 2024
• First Posted (Actual): May 28, 2024

Study Record Updates

• Last Update Posted (Actual): March 10, 2026
• Last Update Submitted That Met QC Criteria: February 17, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Safety; Influenza; Immunogenicity; Reactogenicity; mRNA vaccine; Healthy older adults; Healthy younger adults
• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; Orthomyxoviridae Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Influenza, Human; Biological Products; Complex Mixtures; Vaccines; Viral Vaccines; Influenza Vaccines
• Other Study ID Numbers: 222853

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Qualified researchers may request access to anonymized individual patient-level data (IPD) and related study documents of the eligible studies via the Data Sharing Portal. Details on GSK's data sharing criteria can be found at: https://www.gsk.com/en-gb/innovation/trials/data-transparency/
• 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 terminated asset(s) 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
• product manufactured in and exported from the U.S.: No