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NCT Number: NCT07431853

A Study to Learn About mRNA Vaccines Against Influenza in Adults

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.

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Key information

Conditions

Healthy Adults Infections Influenza, Human Orthomyxoviridae Infections RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

AMR Clinical, Mobile, Alabama, United States

Loading trial locations.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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).

Treatment and study plan

Vaccine Candidate #1

Biological

Investigational influenza Vaccine

Vaccine Candidate #2

Biological

Investigational influenza Vaccine

Vaccine Candidate #3

Biological

Investigational Influenza Vaccine

Vaccine Candidate #4

Biological

Investigational Influenza Vaccine

Vaccine Candidate #5

Biological

Investigational Influenza Vaccine

Vaccine Candidate #6

Biological

Investigational Influenza Vaccine

TIV1 or TIV2

Biological

Licensed influenza vaccine

Primary outcomes

  1. Percentage of participants reporting prespecified local reactions following vaccination

    Time frame: Within 7 days after vaccination

  2. Percentage of participants reporting prespecified systemic events following vaccination.

    Time frame: Within 7 days after vaccination

  3. Percentage of participants reporting adverse events (AEs) following vaccination.

    Time frame: Within 1 month after vaccination

  4. Percentage of participants reporting serious adverse events (SAEs) following vaccination.

    Time frame: Within 6 months after vaccination

  5. Percentage of participants reporting newly diagnosed chronic medical conditions (NDCMCs) following vaccination.

    Time frame: Within 6 months after vaccination

Secondary outcomes

  1. 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

  2. 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

  3. Percentage of participants with satisfactory antibody response to the vaccine.

    Time frame: Before vaccination to 4 weeks after vaccination

Study contacts

Contact information is provided by the study sponsor or research team.

Pfizer CT.gov Call Center

CONTACT

[email protected]

1-800-718-1021

Sponsors and collaborators

Lead sponsor

Pfizer

Industry

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Feb 25, 2026
Registry last updated
May 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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