Last updated: 03/23/2026 06:01:02

A Study to Evaluate the Immune Response and Safety of an Influenza Vaccine in Adults 18 Years of Age and Above

GSK study ID
300336
Clinicaltrials.gov ID
EudraCT ID
Not applicable
EU CT Number
Trial status
Active, not recruiting
Active, not recruiting
Overview
Eligibility
Locations
Study documents
Results summary
Plain language summaries
Additional information

Trial overview

Official title: A Phase 2a Randomized, Observer-Blind, Study to Evaluate the Immunogenicity and Safety of mRNA-Based Multivalent Seasonal Influenza Vaccine Candidates in Adults 18 Years of Age and Older
Trial description: The purpose of this study is to assess the reactogenicity, safety and immune response
of GlaxoSmithKline's (GSK) messenger RNA (mRNA)-based multivalent seasonal influenza vaccine candidates administered in healthy younger and older adults.
Primary purpose:
Prevention
Trial design:
Parallel
Masking:
Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Allocation:
Randomized
Primary outcomes:

Geometric Mean Titer (GMT) Of Antigen 1 Titer

Timeframe: At Day 29

Geometric Mean Increase (GMI) of Antigen 1 Titer

Timeframe: From Day 1 to Day 29

Percentage of Participants with Antigen 1 Seroconversion Rate (SCR)

Timeframe: From Day 1 to Day 29

Percentage of Participants with Antigen 1 Seroprotection Rate (SPR)

Timeframe: At Day 1 and Day 29

Number of Participants with Solicited Administration Site Adverse Events (AEs)

Timeframe: From Day 1 to Day 7

Number of Participants with Solicited Systemic AEs

Timeframe: From Day 1 to Day 7

Number of Participants with Unsolicited AEs

Timeframe: From Day 1 to Day 28

Number of Participants with Serious Adverse Events (SAEs)

Timeframe: From Day 1 to Day 181 (study end)

Number of Participants with Adverse Events of Special Interest (AESIs)

Timeframe: From Day 1 to Day 181 (study end)

Number of Participants with Medically Attended Adverse Events (MAAEs)

Timeframe: From Day 1 to Day 181 (study end)

Number of Participants with any Laboratory abnormalities

Timeframe: From Day 1 to Day 29

Secondary outcomes:

GMT Ratio of Antigen 2 Titer

Timeframe: At Day 29

GMI of Antigen 2 Titer

Timeframe: From Day 1 to Day 29

Percentage of Participants with Antigen 2 SCR

Timeframe: From Day 1 to Day 29

Interventions:
Biological/vaccine: Flu mRNA (Formulation B1)
Biological/vaccine: Flu mRNA (Formulation B3)
Biological/vaccine: Flu mRNA(Formulation A)
Combination product: Comparator 1
Combination product: Comparator 2
Combination product: Comparator 3
Enrollment:
971
Observational study model:
Not applicable
Primary completion date:
2026-31-07
Time perspective:
Not applicable
Clinical publications:
Not applicable
Medical condition
Influenza, Human
Product
Not applicable
Collaborators
Not applicable
Study date(s)
October 2025 to July 2026
Type
Interventional
Phase
2

Participation criteria

Sex
Female & Male
Age
18+ years
Accepts healthy volunteers
Yes
  • 1. Participants, who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g., completion of the eDiary, attendance to study contacts and study site visits, and ability to access and utilize a phone or other electronic communications) independently or with the assistance of a caregiver.
  • 2. Written (physically, or digitally) informed consent obtained from the participant prior to performance of any study-specific procedure.
  • 1. Where applicable, FDA toxicity grades will be exclusionary.
  • 2. Current or chronic conditions related with EXC criteria 1.

Trial location(s)

Location
Status
Contact us
Contact us
Location
GSK Investigational Site
Austin, TX, Unmapped, 78705
Status
Unmapped
Location
GSK Investigational Site
Garland, TX, Unmapped, 75043
Status
Unmapped
Location
GSK Investigational Site
Greensboro, NC, Unmapped, 27408
Status
Unmapped
Location
GSK Investigational Site
Hialeah, FL, Unmapped, 33012
Status
Unmapped
Location
GSK Investigational Site
Newport News, VA, Unmapped, 23606
Status
Unmapped
Location
GSK Investigational Site
Miami, FL, Unmapped, 33186
Status
Unmapped
Location
GSK Investigational Site
Pembroke Pines, FL, Unmapped, 33025
Status
Unmapped
Location
GSK Investigational Site
Guntersville, AL, Unmapped, 35976
Status
Unmapped
Location
GSK Investigational Site
Stockbridge, GA, Unmapped, 30281
Status
Unmapped
Location
GSK Investigational Site
North Charleston, SC, Unmapped, 29405
Status
Unmapped
Location
GSK Investigational Site
Edegem, Belgium, 2650
Status
Unmapped
Location
GSK Investigational Site
Gent, Belgium, 9000
Status
Unmapped
Location
GSK Investigational Site
Walnut Creek, CA, Unmapped, 94598
Status
Unmapped
Location
GSK Investigational Site
Canoga Park, CA, Unmapped, 91303
Status
Unmapped
Location
GSK Investigational Site
Carson City, NV, Unmapped, 89706
Status
Unmapped
Location
GSK Investigational Site
Las Vegas, NV, Unmapped, 89109
Status
Unmapped
Location
GSK Investigational Site
Seattle, WA, Unmapped, 98104
Status
Unmapped

Study documents

No study documents available.

Results overview

Study Results yet to be posted

Recruitment status
Active, not recruiting
Actual primary completion date
Not applicable
Actual study completion date
Not applicable

Plain language summaries

Plain language summaries of clinical trial results for Phase 2-4 clinical trials that were initiated on or after January 2022 will be posted by GSK within one year following study completion.

Additional information about the trial

Additional information
Not applicable
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