Sanofi's COVID-19 vaccine shows promise in early trial

NCT ID NCT04537208

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

First seen Jun 26, 2026 · Last updated Jun 26, 2026

Summary

This study tested a new COVID-19 vaccine made from a piece of the virus's spike protein, given with or without an immune booster (adjuvant). 441 healthy adults aged 18 and older received one of several vaccine formulas. The goal was to see how well the vaccine triggered an immune response and whether it was safe over 12 months.

What this could mean

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

Active substance: SARS-CoV-2 recombinant protein vaccine with or without adjuvant (AF03 or AS03)
What this could lead to: If successful, this vaccine could help protect against COVID-19 by triggering a strong immune response.
What could go wrong: This is an early-phase trial (Phase 1/2) with only 441 participants, so results may not apply to larger populations. The vaccine may not provide lasting protection or work against new variants.

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

As listed by the trial registrant

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

COVID-19 (HEALTHY VOLUNTEERS)

Contacts and locations

Locations

Investigational Site Number 8400001

Rochester, New York, 14609, United States
Investigational Site Number 8400002

Omaha, Nebraska, 68134, United States
Investigational Site Number 8400003

Philadelphia, Pennsylvania, 19104, United States
Investigational Site Number 8400004

Birmingham, Alabama, 35294, United States
Investigational Site Number 8400007

Rochester, New York, 14642, United States
Investigational Site Number 8400008

Cleveland, Ohio, 44122, United States
Investigational Site Number 8400011

Hollywood, Florida, 33024, United States
Investigational Site Number 8400012

Rolling Hills Estates, California, 90274, United States
Investigational Site Number 8400014

Mt. Pleasant, South Carolina, 29464, United States
Investigational Site Number 8400016

Boston, Massachusetts, 02115, United States
Investigational Site Number 8400019

Melbourne, Florida, 32934, United States