A Study to Learn About mRNA Vaccines Against Influenza in Adults

May 4, 2026 updated by: Pfizer

A PHASE 2, RANDOMIZED, DOUBLE-BLIND, CLINICAL STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF MRNA VACCINES AGAINST INFLUENZA IN ADULTS 18 YEARS OF AGE AND OLDER

The purpose of this study is to learn about safety in participants taking the study vaccine (mRNA-based vaccine) and the ability of the study vaccine to trigger the body's immune response, targeting the flu virus (influenza virus).

This study is seeking healthy participants 18 years of age or older. All participants in this study will receive only 1 dose in their arm, to deliver one of the experimental flu vaccines or one of the approved flu vaccines used for comparison.

Participants will take part in this study for about 6 months, and participants will need to visit the study site at least 3 times. A blood sample will be taken at each of the 3 planned study visits and a swab from inside the nose will be taken at the first study visit.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

770

Phase

  • Phase 2

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 Locations

  • United States
    • Alabama
      • Mobile, Alabama, United States, 36608
        • Recruiting
        • AMR Clinical
    • California
      • Walnut Creek, California, United States, 94598
        • Recruiting
        • Diablo Clinical Research, LLC d/b/a Flourish Research
    • Connecticut
      • Milford, Connecticut, United States, 06460
        • Recruiting
        • Clinical Research Consulting, LLC
    • District of Columbia
      • Washington D.C., District of Columbia, United States, 20037
        • Recruiting
        • George Washington Medical Faculty Associates
    • Florida
      • Hialeah, Florida, United States, 33012
        • Recruiting
        • Indago Research & Health Center, Inc
      • Miami Lakes, Florida, United States, 33014
        • Recruiting
        • Palm Springs Community Health Center
    • Georgia
      • Stockbridge, Georgia, United States, 30281
        • Recruiting
        • Clinical Research Atlanta
    • Hawaii
      • Honolulu, Hawaii, United States, 96814
        • Recruiting
        • East-West Medical Research Institute
    • Missouri
      • Kansas City, Missouri, United States, 64114
        • Recruiting
        • AMR Clinical
    • New York
      • Rochester, New York, United States, 14609
        • Recruiting
        • Rochester Clinical Research, LLC
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19107
        • Recruiting
        • DM Clinical Research - Philadelphia
    • Texas
      • Mesquite, Texas, United States, 75149
        • Recruiting
        • SMS Clinical Research LLC
      • Tomball, Texas, United States, 77375
        • Recruiting
        • DM Clinical Research
    • Utah
      • Salt Lake City, Utah, United States, 84109
        • Recruiting
        • J. Lewis Research, Inc. / Foothill Family Clinic
    • Virginia
      • Charlottesville, Virginia, United States, 22911
        • Recruiting
        • Charlottesville Medical Research Center, LLC

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria

• Healthy and medically stable participants who are determined by medical history, physical examination (if clinically required), and clinical judgment of the investigator to be eligible for inclusion in the study.

Exclusion Criteria

  • Tested positive for influenza ≤5 months (150 days) prior to Visit 1 (Day 1).
  • Vaccination with any investigational or licensed influenza vaccine ≤5 months (150 days) before Visit 1 (Day 1).
  • Receipt of antiviral therapies for influenza (eg, Tamiflu) ≤5 months (150 days) prior to Visit 1 (Day 1).

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: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: A
mRNA influenza vaccine candidate #1 as a single intramuscular (IM) injection on Day 1.
Biological: Vaccine Candidate #1
Investigational influenza Vaccine
Experimental: B
mRNA influenza vaccine candidate #2 as a single IM injection on Day 1.
Biological: Vaccine Candidate #2
Investigational influenza Vaccine
Experimental: C
mRNA influenza vaccine candidate #3 as a single IM injection on Day 1.
Biological: Vaccine Candidate #3
Investigational Influenza Vaccine
Experimental: D
mRNA influenza vaccine candidate #4 as a single IM injection on Day 1.
Biological: Vaccine Candidate #4
Investigational Influenza Vaccine
Experimental: E
mRNA influenza vaccine candidate #5 as a single IM injection on Day 1.
Biological: Vaccine Candidate #5
Investigational Influenza Vaccine
Experimental: F
mRNA influenza vaccine candidate #6 as a single IM injection on Day 1.
Biological: Vaccine Candidate #6
Investigational Influenza Vaccine
Active Comparator: G
Licensed influenza vaccine (TIV1 or TIV2) as a single IM injection.
Biological: TIV1 or TIV2
Licensed influenza vaccine

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Percentage of participants reporting prespecified local reactions following vaccination
Time Frame: Within 7 days after vaccination
Within 7 days after vaccination
Percentage of participants reporting prespecified systemic events following vaccination.
Time Frame: Within 7 days after vaccination
Within 7 days after vaccination
Percentage of participants reporting adverse events (AEs) following vaccination.
Time Frame: Within 1 month after vaccination
Within 1 month after vaccination
Percentage of participants reporting serious adverse events (SAEs) following vaccination.
Time Frame: Within 6 months after vaccination
Within 6 months after vaccination
Percentage of participants reporting newly diagnosed chronic medical conditions (NDCMCs) following vaccination.
Time Frame: Within 6 months after vaccination
Within 6 months after vaccination

Secondary Outcome Measures

Outcome Measure
Time Frame
Geometric Mean Titer (GMT) of Anti-Influenza Antibody Levels to each of the influenza antigens of the vaccine.
Time Frame: Before vaccination and at 4 weeks after vaccination
Before vaccination and at 4 weeks after vaccination
Geometric Mean Fold Rise (GMFR) of Anti-Influenza Antibody Levels to each of the influenza antigens of the vaccine
Time Frame: Before vaccination to 4 weeks after vaccination
Before vaccination to 4 weeks after vaccination
Percentage of participants with satisfactory antibody response to the vaccine.
Time Frame: Before vaccination to 4 weeks after vaccination
Before vaccination to 4 weeks after vaccination

Collaborators and Investigators

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

Sponsor

Pfizer

Investigators

  • Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

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)

February 23, 2026

Primary Completion (Estimated)

June 22, 2027

Study Completion (Estimated)

June 22, 2027

Study Registration Dates

First Submitted

February 19, 2026

First Submitted That Met QC Criteria

February 19, 2026

First Posted (Actual)

February 25, 2026

Study Record Updates

Last Update Posted (Actual)

May 6, 2026

Last Update Submitted That Met QC Criteria

May 4, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • C6481001

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

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

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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