A Study About Modified RNA Vaccines Against Influenza in Healthy Adults

January 7, 2026 updated by: Pfizer

A STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF MODIFIED RNA VACCINES AGAINST INFLUENZA IN HEALTHY ADULTS

The purpose of this study is to learn if modified RNA (modRNA) vaccines for the prevention of influenza are:

  • safe; and
  • how these vaccines produce an immune response in generally healthy adults. Immune response is the way the body protects itself against things it sees as harmful or foreign.

RNA (also called ribonucleic acid) is one of two types of nucleic acid made by cells. RNA contains information that has been copied from DNA (the other type of nucleic acid). Cells make several different forms of RNA, and each form has a specific job in the cell. Many forms of RNA have functions related to making proteins. RNA is also the genetic material of some viruses instead of DNA. RNA can be made in the laboratory and used in research studies. Also called ribonucleic acid.

Influenza is term used for flu illness. It is an infection caused by a virus that affects your mouth, nose, and throat.

The study is seeking for participants who:

  • are at least 18 years of age
  • have not received an influenza vaccine within the last 6 months
  • are generally healthy

This study will be divided into three sub-studies: Substudy A (SSA), Substudy B (SSB), and Substudy C (SSC).

All participants, regardless of sub-study, will receive 1 dose of either of the following vaccines as an injection into their arm:

  • 1 of the modRNA influenza vaccines that is being studied; or
  • an approved influenza vaccine approved for use in their respective age group.

Participants will be involved in this study for about 6 months. During this time, participants will have at least 3 clinic visits.

Study Overview

Study Type

Interventional

Enrollment (Actual)

1202

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 Locations

    • Alabama
      • Mobile, Alabama, United States, 36608
        • Alliance for Multispecialty Research, LLC
    • Arizona
      • Scottsdale, Arizona, United States, 85260
        • Headlands Research - Scottsdale
    • California
      • Anaheim, California, United States, 92801
        • Anaheim Clinical Trials, LLC
      • Lake Forest, California, United States, 92630
        • Orange County Research Center
      • San Diego, California, United States, 92103
        • Artemis Institute for Clinical Research
      • Walnut Creek, California, United States, 94598
        • Diablo Clinical Research, Inc.
    • Connecticut
      • Milford, Connecticut, United States, 06460
        • Clinical Research Consulting
    • Florida
      • Hialeah, Florida, United States, 33012
        • Indago Research & Health Center, Inc
      • Hollywood, Florida, United States, 33024
        • Research Centers of America
      • Hollywood, Florida, United States, 33024
        • Research Centers of America ( Hollywood )
      • Miami Lakes, Florida, United States, 33014
        • Palm Springs Community Health Center
      • Orlando, Florida, United States, 32801
        • Clinical Neuroscience Solutions, Inc.
      • Orlando, Florida, United States, 32819
        • Headlands Research Orlando
      • South Miami, Florida, United States, 33143
        • Qps-Mra, Llc
    • Hawaii
      • Honolulu, Hawaii, United States, 96814
        • East-West Medical Research Institute
    • Louisiana
      • New Orleans, Louisiana, United States, 70119
        • Alliance for Multispecialty Research, LLC
    • Minnesota
      • Saint Paul, Minnesota, United States, 55114
        • Prism Research LLC dba Nucleus Network
    • Missouri
      • Chesterfield, Missouri, United States, 63005
        • Clinical Research Professionals
      • Kansas City, Missouri, United States, 64114
        • Alliance for Multispecialty Research, LLC
    • New York
      • Rochester, New York, United States, 14609
        • Rochester Clinical Research, LLC
    • North Carolina
      • Durham, North Carolina, United States, 27703
        • Duke Vaccine and Trials Unit
      • Raleigh, North Carolina, United States, 27612
        • M3 Wake Research, Inc.
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19107
        • DM Clinical Research - Philadelphia
    • Texas
      • Brownsville, Texas, United States, 78526
        • Headlands Horizons LLC
      • Mesquite, Texas, United States, 75149
        • SMS Clinical Research
      • San Antonio, Texas, United States, 78229
        • Clinical Trials of Texas, LLC
      • San Antonio, Texas, United States, 78229
        • Clinical Trials of Texas, LLC dba Flourish Research
      • Tomball, Texas, United States, 77375
        • Dynamed Clinical Research, LP d/b/a DM Clinical Research
    • Utah
      • Salt Lake City, Utah, United States, 84109
        • J. Lewis Research, Inc. / Foothill Family Clinic
      • Salt Lake City, Utah, United States, 84121
        • J. Lewis Research, Inc. / Foothill Family Clinic South
    • Virginia
      • Charlottesville, Virginia, United States, 22911
        • Charlottesville Medical Research
      • Norfolk, Virginia, United States, 23502
        • Alliance for Multispecialty Research, 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

Key Inclusion Criteria

Applies to all 3 substudies:

  • participants ≥18 years of age.
  • generally healthy participants.

Substudy C ONLY:

- receipt of licensed influenza vaccination for the 2023-2024 flu season at least 6 months ago.

Key Exclusion Criteria

All 3 substudies:

  • diagnosis of influenza (by clinical testing) in the last 6 months.
  • immunocompromised individuals with known or suspected immunodeficiency
  • receipt of any investigational or licensed influenza vaccines within 6 months.

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: SSA: Influenza ModRNA Vaccine 2A
- Single Dose on Day 1
Intramuscular injection
Experimental: SSA: Influenza ModRNA Vaccine 3A
- Single Dose on Day 1
Intramuscular injection
Experimental: SSA: Influenza ModRNA Vaccine 4A
- Single Dose on Day 1
Intramuscular injection
Experimental: SSA: Influenza ModRNA Vaccine 5A
- Single dose on Day 1
Intramuscular injection
Active Comparator: SSA: QIV1
- Single dose on Day 1
Intramuscular injection
Experimental: SSB: Influenza ModRNA Vaccine 3B
- Single Dose on Day 1
Intramuscular injection
Experimental: SSB: Influenza ModRNA Vaccine 4B
- Single Dose on Day 1
Intramuscular injection
Experimental: SSB: Influenza ModRNA Vaccine 5B
- Single dose on Day 1
Intramuscular injection
Active Comparator: SSB: QIV2
- Single Dose on Day 1
Intramuscular injection
Active Comparator: SSB: QIV3
- Single Dose on Day 1
Intramuscular injection
Experimental: SSC: Influenza ModRNA Vaccine 3C
- Single Dose on Day 1
Intramuscular injection
Experimental: SSC: Influenza ModRNA Vaccine 4C
- Single Dose on Day 1
Intramuscular injection
Experimental: SSC: Influenza ModRNA Vaccine 5C
- Single Dose on Day 1
Intramuscular injection
Experimental: SSC: Influenza ModRNA Vaccine 6C
- Single Dose on Day 1
Intramuscular injection
Experimental: SSC: Influenza ModRNA Vaccine 7C
- Single Dose on Day 1
Intramuscular injection
Experimental: SSC: Influenza ModRNA Vaccine 8C
- Single Dose on Day 1
Intramuscular injection
Experimental: SSC: Influenza ModRNA Vaccine 9C
- Single dose on Day 1
Intramuscular injection
Active Comparator: SSC: QIV2
- Single Dose on Day 1
Intramuscular injection
Active Comparator: SSC: QIV3
- Single Dose on Day 1
Intramuscular injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
SSA - Percentage of Participants Reporting Local Reactions After Vaccination
Time Frame: From Day 1 Through at least Day 7 After Vaccination
Pain at the injection site, redness, and swelling.
From Day 1 Through at least Day 7 After Vaccination
SSA - Percentage of Participants Reporting Systemic Events After Vaccination
Time Frame: From Day 1 Through at least Day 7 After Vaccination
Fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, and new or worsened joint pain.
From Day 1 Through at least Day 7 After Vaccination
SSA - Percentage of Participants Reporting Adverse Events After Vaccination
Time Frame: From Day 1 Through 4 Weeks After Vaccination
As elicited by investigational site staff
From Day 1 Through 4 Weeks After Vaccination
SSA - Percentage of Participants Reporting Serious Adverse Events (SAE)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination
SSA - Percentage of Participants Reporting Newly Diagnosed Chronic Medical Conditions (NDCMCs)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination
SSA - Percentage of Participants Reporting Medically Attended AEs (MAEs)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination
SSB - Percentage of Participants Reporting Local Reactions After Vaccination
Time Frame: From Day 1 Through at least Day 7 After Vaccination
Pain at injection site, redness, and swelling.
From Day 1 Through at least Day 7 After Vaccination
SSB - Percentage of Participants Reporting Systemic Events After Vaccination
Time Frame: From Day 1 Through at least Day 7 After Vaccination
Fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, and new or worsened joint pain.
From Day 1 Through at least Day 7 After Vaccination
SSB - Percentage of Participants Reporting Adverse Events After Vaccination
Time Frame: From Day 1 Through 4 Weeks After Vaccination
As elicited by investigational site staff
From Day 1 Through 4 Weeks After Vaccination
SSB - Percentage of Participants Reporting Serious Adverse Events (SAE)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination
SSB - Percentage of Participants Reporting Newly Diagnosed Chronic Medical Conditions (NDCMCs)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination
SSB - Percentage of Participants Reporting Medically Attended AEs (MAEs)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination
SSC - Percentage of Participants Reporting Local Reactions After Vaccination
Time Frame: From Day 1 Through at least Day 7 After Vaccination
Pain at the injection site, redness, and swelling.
From Day 1 Through at least Day 7 After Vaccination
SSC - Percentage of Participants Reporting Systemic Events After Vaccination
Time Frame: From Day 1 Through at least Day 7 After Vaccination
Fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, and new or worsened joint pain.
From Day 1 Through at least Day 7 After Vaccination
SSC - Percentage of Participants Reporting Adverse Events After Vaccination
Time Frame: From Day 1 Through 4 Weeks After Vaccination
As elicited by investigational site staff
From Day 1 Through 4 Weeks After Vaccination
SSC - Percentage of Participants Reporting Serious Adverse Events (SAE)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination
SSC - Percentage of Participants Reporting Newly Diagnosed Chronic Medical Conditions (NDCMCs)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination
SSC - Percentage of Participants Reporting Medically Attended AEs (MAEs)
Time Frame: From Day 1 Through 6 Months After Vaccination
As elicited by investigational site staff
From Day 1 Through 6 Months After Vaccination

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
SSA - HAI Geometric Mean Titers (GMTs) for each strain
Time Frame: 4 Weeks After Vaccination
As measured at the central laboratory
4 Weeks After Vaccination
SSA - HAI geometric mean fold rise (GMFR) for each strain
Time Frame: 4 Weeks After Vaccination
As measured at the central laboratory
4 Weeks After Vaccination
SSA - The proportion of participants achieving HAI seroconversion for each strain
Time Frame: 4 Weeks After Vaccination
As measured at the central laboratory
4 Weeks After Vaccination
SSA - The proportion of participants with HAI titers ≥1:40 for each strain
Time Frame: Baseline and 4 Weeks After Vaccination
As measured at the central laboratory
Baseline and 4 Weeks After Vaccination
SSB - HAI geometric mean titers (GMTs) for each strain
Time Frame: 4 Weeks After Vaccination
As measured at the central laboratory
4 Weeks After Vaccination
SSB - HAI geometric mean fold rise (GMFR) for each strain
Time Frame: 4 Weeks After Vaccination
As measured at the central laboratory
4 Weeks After Vaccination
SSB - The proportion of participants achieving HAI seroconversion for each strain
Time Frame: 4 Weeks After Vaccination
As measured at the central laboratory
4 Weeks After Vaccination
SSB - The proportion of participants with HAI titers ≥1:40 for each strain
Time Frame: Baseline and 4 Weeks After Vaccination
As measured at the central laboratory
Baseline and 4 Weeks After Vaccination

Collaborators and Investigators

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

Sponsor

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.

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)

May 23, 2024

Primary Completion (Actual)

February 5, 2025

Study Completion (Actual)

February 5, 2025

Study Registration Dates

First Submitted

May 24, 2024

First Submitted That Met QC Criteria

May 30, 2024

First Posted (Actual)

May 31, 2024

Study Record Updates

Last Update Posted (Actual)

January 9, 2026

Last Update Submitted That Met QC Criteria

January 7, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

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

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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