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A Study to Learn About mRNA Vaccines Against Influenza in Adults

This study is looking for healthy adults, aged 18 and older, to help us learn more about investigational mRNA vaccines for the flu. We want to understand how safe these vaccines are and how well they help your body create an immune response against the flu virus. You will receive one dose of either an experimental flu vaccine (Vaccine Candidate #1, #2, #3, #4, or #5) or an approved flu vaccine. We will be checking for any reactions you might have after vaccination and any other side effects. The study aims to enroll about 770 participants.

Study design
This study is an interventional study, meaning participants will receive a specific treatment. It plans to enroll about 770 healthy adults.
What's involved
You will participate for about 6 months and need to visit the study site at least 3 times. You will have blood samples taken at each visit and a nose swab at the first visit.
Compensation
Not stated in the trial record.
Follow-up
Participants will be monitored for local and systemic reactions for 7 days after vaccination, and for other adverse events for up to 1 month after vaccination.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT07431853

A Study to Learn About mRNA Vaccines Against Influenza in Adults

Recruiting
PHASE2Ages 18+InterventionalPrevention
Pfizer
~770 participants
Updated 2026-05-06 on ClinicalTrials.gov
What's tested:Vaccine Candidate #1Vaccine Candidate #2Vaccine Candidate #3Vaccine Candidate #4Vaccine Candidate #5Vaccine Candidate #6

At a glance

Recruiting sites
15 of 15 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Percentage of participants reporting prespecified local reactions following vaccination
Measured over Within 7 days after vaccination
+4 more outcomes measured

Conditions

Healthy Adults

Explore related trials

Influenza

Where it's being run

15 sites across 13 states
Florida2
Texas2
Alabama1
California1
Connecticut1
District of Columbia1
Georgia1
Hawaii1

Study leadership

  • Pfizer CT.gov Call Center · STUDY_DIRECTOR · Pfizer

Who to contact

Pfizer CT.gov Call Center
[email protected]
1-800-718-1021
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Exclusion

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).

What this trial measures

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