MRNA tech takes on the flu: could new shots outsmart seasonal strains?

NCT ID NCT06361875

Completed ⭐️ VACCINE ⭐️ Sponsor: Sanofi Pasteur, a Sanofi Company Source: ClinicalTrials.gov ↗

First seen Aug 04, 2026 · Last updated Aug 05, 2026 · Updated 1 time

Summary

This trial is testing three experimental mRNA-based flu vaccines in healthy adults aged 18 and older. The goal is to see how safe they are and how well they trigger an immune response compared to standard flu vaccines. Participants receive a single injection, and researchers monitor side effects and measure antibody levels over the following month.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: Quadrivalent influenza mRNA vaccines (MRT5421, MRT5424, MRT5429)
What this could lead to: If successful, these mRNA-based flu vaccines could offer a faster, more adaptable alternative to traditional flu shots, potentially improving protection each season.
What could go wrong: This is an early-stage trial, so the vaccines may not prove safe or effective in larger populations. Possible side effects include injection-site reactions, fever, and rare serious events like myocarditis.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

influenza prevention target

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

HEALTHY VOLUNTEERS INFLUENZA IMMUNIZATION

Contacts and locations

Locations

AMR Knoxville- Site Number : 8400043

Knoxville, Tennessee, 37909, United States
AMR Lexington- Site Number : 8400042

Lexington, Kentucky, 40509, United States
Brengle Family Medicine Site Number : 8400045

Indianapolis, Indiana, 46260, United States
California Research Foundation Site Number : 8400038

San Diego, California, 92123-1881, United States
Cenexel JBR- Site Number : 8400051

Salt Lake City, Utah, 84107, United States
Cenexel Research Centers of America- Site Number : 8400037

Hollywood, Florida, 33024, United States
Clinical Trials of Texas, Inc. - PPDS- Site Number : 8400029

San Antonio, Texas, 78229, United States
Indago Research and Health Center- Site Number : 8400032

Hialeah, Florida, 33012, United States
Investigational Site Number : 3400001

San Pedro Sula, 21104, Honduras
Investigational Site Number : 6300002

Barrio Sabana, 00694, Puerto Rico
The Alliance for Multispecialty Research - KCM, LLC- Site Number : 8400034

Kansas City, Missouri, 64114, United States
Velocity Clinical Research Norfolk- Site Number : 8400046

Norfolk, Nebraska, 68701, United States
Velocity Clinical Research- New Orleans Site Number : 8400053

New Orleans, Louisiana, 70119, United States

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