New mRNA vaccine shows promise against common virus that can harm newborns

NCT ID NCT04232280

Completed ⭐️ VACCINE ⭐️ Sponsor: ModernaTX, Inc. Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This study tested an experimental mRNA vaccine called mRNA-1647 to see if it is safe and triggers an immune response against cytomegalovirus (CMV). The trial involved 315 healthy adults aged 18 to 40, some of whom had never been exposed to CMV. Researchers measured side effects and antibody levels after vaccination. The goal is to develop a vaccine that could prevent CMV infection, which can cause serious problems in newborns and people with weak immune systems.

What this could mean

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

Active substance: mRNA-1647 vaccine
What this could lead to: If successful, this vaccine could help prevent cytomegalovirus infection, which is a leading cause of birth defects and complications in people with weakened immune systems.
What could go wrong: This is an early phase 2 trial with only 315 participants, so the vaccine may not work as well in larger, more diverse populations. Side effects like injection site pain, headache, and fatigue were common.

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Conditions

The condition(s) this trial relates to.

DNA Virus Infections viral infectious disease cytomegalovirus infection prevention target

As listed by the trial registrant

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

CYTOMEGALOVIRUS INFECTION

Contacts and locations

Locations

Alliance for Multispecialty Research

Lexington, Kentucky, 40509, United States
Aventiv Research Inc

Columbus, Ohio, 43213-6523, United States
Benchmark Research

Sacramento, California, 95864, United States
Crossroads Clinical Research

Victoria, Texas, 77901, United States
Foothill Family Clinic

Salt Lake City, Utah, 84109, United States
Foothill Family Clinic-South Clinic

Salt Lake City, Utah, 84121, United States
Johnson County Clin-Trials

Lenexa, Kansas, 66219, United States
Optimal Research

Peoria, Illinois, 61614, United States
Tekton Research Inc

Austin, Texas, 78745, United States

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