One-Stop shot? study combines flu and COVID boosters for seniors

NCT ID NCT04969276

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

First seen Jun 24, 2026 · Last updated Jun 26, 2026 · Updated 2 times

Summary

This study looked at whether it's safe and effective to give a high-dose flu vaccine and a Moderna COVID-19 booster at the same time to adults 65 and older. 306 volunteers who had already received two Moderna shots took part. Researchers measured side effects and antibody levels to see if getting both vaccines together worked as well as getting them separately.

What this could mean

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

Active substance: Fluzone High-Dose Quadrivalent influenza vaccine and Moderna COVID-19 vaccine (mRNA-1273)
What this could lead to: If successful, this could show that getting a flu shot and a COVID-19 booster at the same time is safe and effective for older adults, simplifying vaccination schedules.
What could go wrong: This is a phase 2 study with only 306 participants, so results may not apply to everyone. The study is completed, but it primarily measured immune response and short-term side effects, not long-term protection.

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.

COVID-19 prevention target 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

Investigational Site Number :8400001

Peoria, Illinois, 61614, United States
Investigational Site Number :8400002

Austin, Texas, 78705, United States
Investigational Site Number :8400003

Glendale, Arizona, 85306, United States
Investigational Site Number :8400004

Vista, California, 92083, United States
Investigational Site Number :8400005

Centennial, Colorado, 80112, United States
Investigational Site Number :8400006

San Diego, California, 92108, United States

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