Recruiting
Phase 2

mRNA Vaccine

Sponsor:

Pfizer

Code:

NCT07431853

Conditions

Healthy Adults

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

Interventions

Vaccine Candidate #1

Vaccine Candidate #2

Vaccine Candidate #3

Vaccine Candidate #4

Vaccine Candidate #5

Study Details

Brief summary:

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.

Conditions

Healthy Adults

Study ID

NCT07431853

Start date

Feb 23, 2026

Status verified date

May, 2026

Completion date

Jun 22, 2027

Anticipated

Primary completion date

Jun 22, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Accepted

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 Design

Enrollment

770 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

experimental: A

mRNA influenza vaccine candidate #1 as a single intramuscular (IM) injection on Day 1.

experimental: B

mRNA influenza vaccine candidate #2 as a single IM injection on Day 1.

experimental: C

mRNA influenza vaccine candidate #3 as a single IM injection on Day 1.

experimental: D

mRNA influenza vaccine candidate #4 as a single IM injection on Day 1.

experimental: E

mRNA influenza vaccine candidate #5 as a single IM injection on Day 1.

experimental: F

mRNA influenza vaccine candidate #6 as a single IM injection on Day 1.

active comparator: G

Licensed influenza vaccine (TIV1 or TIV2) as a single IM injection.

Interventions

Vaccine Candidate #1

Investigational influenza Vaccine

Vaccine Candidate #2

Investigational influenza Vaccine

Vaccine Candidate #3

Investigational Influenza Vaccine

Vaccine Candidate #4

Investigational Influenza Vaccine

Vaccine Candidate #5

Investigational Influenza Vaccine

Vaccine Candidate #6

Investigational Influenza Vaccine

TIV1 or TIV2

Licensed influenza vaccine

Primary outcome measure

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

Central Contacts and Locations

Central contacts

Pfizer CT.gov Call Center

1-800-718-1021ClinicalTrials.gov_Inquiries@pfizer.com

Locations

AMR Clinical

Recruiting

Mobile, Alabama, United States, 36608

Diablo Clinical Research, LLC d/b/a Flourish Research

Recruiting

Walnut Creek, California, United States, 94598

Clinical Research Consulting, LLC

Recruiting

Milford, Connecticut, United States, 06460

George Washington Medical Faculty Associates

Recruiting

Washington D.C., District of Columbia, United States, 20037

Indago Research & Health Center, Inc

Recruiting

Hialeah, Florida, United States, 33012

Palm Springs Community Health Center

Recruiting

Miami Lakes, Florida, United States, 33014

Clinical Research Atlanta

Recruiting

Stockbridge, Georgia, United States, 30281

East-West Medical Research Institute

Recruiting

Honolulu, Hawaii, United States, 96814

AMR Clinical

Recruiting

Kansas City, Missouri, United States, 64114

Rochester Clinical Research, LLC

Recruiting

Rochester, New York, United States, 14609

DM Clinical Research - Philadelphia

Recruiting

Philadelphia, Pennsylvania, United States, 19107

SMS Clinical Research LLC

Recruiting

Mesquite, Texas, United States, 75149

DM Clinical Research

Recruiting

Tomball, Texas, United States, 77375

J. Lewis Research, Inc. / Foothill Family Clinic

Recruiting

Salt Lake City, Utah, United States, 84109

Charlottesville Medical Research Center, LLC

Recruiting

Charlottesville, Virginia, United States, 22911

More Information

Sponsor

Pfizer

Last update posted

May 6, 2026

Last verified

May, 2026

Keywords

  • Influenza vaccination

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-08. This information was provided to ClinicalTrials.gov by Pfizer on 2026-05-06.