Home › Trials › NCT07431853

mRNA vaccines against influenza in adults

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

Phase 2 Interventional Pfizer · NCT07431853

This research will test single-dose mRNA flu vaccines in healthy adults to see if they are safe and trigger an immune response.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment770 (estimated)
Ages18 Years and up
SexAll
SponsorPfizer Industry-sponsored
Locations15 sites (Mobile, Alabama and 14 other locations)
Trial IDNCT07431853 on ClinicalTrials.gov

What this trial studies

This Phase 2 interventional trial gives each healthy adult participant a single dose of one experimental mRNA influenza vaccine or a licensed comparator and follows them for about six months. Safety is monitored and blood samples are collected at three scheduled visits to measure immune responses, with a nasal swab taken at the first visit. Multiple vaccine candidates are being compared to understand which formulations produce the strongest antibody response and acceptable safety profiles. The trial is sponsored by a major pharmaceutical company and conducted at several U.S. clinical sites.

Who should consider this trial

Good fit: Healthy adults aged 18 years or older who are medically stable and meet screening criteria are ideal candidates for this study.

Not a fit: People who are not medically healthy or who had influenza, a flu vaccine, or antiviral treatment within the past five months are unlikely to benefit or be eligible.

Why it matters

Potential benefit: If successful, these mRNA flu vaccines could provide faster development and potentially stronger or more flexible protection against influenza than current vaccines.

How similar studies have performed: mRNA vaccines were highly successful for COVID-19 and early-phase mRNA influenza studies have shown promising immune responses, but large-scale effectiveness for flu is not yet proven.

Eligibility criteria

Show full inclusion / exclusion criteria 
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).

Where this trial is running

Mobile, Alabama and 14 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Healthy AdultsInfluenza vaccination
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.