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CytomegalovirusPhase 1/2NCT05575492

A Study of mRNA-1647 Cytomegalovirus Vaccine in Healthy Participants 9 to 15 Years of Age and Participants 16 to 25 Years of Age

A Phase 1/2 study testing mRNA-1647 in people with Cytomegalovirus, run by ModernaTX, Inc. at 57 sites in 3 countries.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

The main purpose of study is to evaluate the safety and immunogenicity of different dose levels of mRNA-1647 versus control in healthy cytomegalovirus (CMV)-seronegative and CMV-seropositive female and male participants 9 to 15 years of age. Read more about this study

Who is it for?
Ages 9 to 25 yearsHealthy volunteers can take part
Conditions the study is for
Cytomegalovirus
What is being tested?
mRNA-1647
Type of treatment
Injection or infusion
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
873 participants
Where
57 sitesin 3 countries
Study dates
7 Nov 2022to 12 May 2026
Phase
Phase 1/2
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 9 to 25 years
  • All sexes
  • Healthy volunteers accepted
  • Child, Adult

Who may be able to join

  • Is a female or male 9 to 15 years of age or is a female 16 to 25 years of age at the time of consent.
  • Is in good general health, in the opinion of the Investigator, and is capable of complying with study procedures.
  • For the CMV-seronegative cohorts: At the Screening visit, is CMV IgG-negative and CMV immunoglobulin M (IgM)-negative.
  • For the CMV-seropositive cohorts: At the Screening visit, is CMV IgG-positive and CMV IgM-negative, CMV IgG-positive and CMV IgM-positive, or CMV IgG-positive and CMV IgM-indeterminate. Participants with an isolated positive or indeterminate result for CMV IgM (that is, CMV IgG-negative and either CMV IgM-positive or CMV IgM-indeterminate) will not be eligible for enrollment but may be rescreened after at least 6 weeks from the initial CMV Screening. Participants with an indeterminate result for CMV IgG, regardless of IgM result, will not be eligible for enrollment but may be rescreened after at least 6 weeks from the initial CMV screening.
  • If 9 to 15 years of age, has a body mass index (BMI) at or above the third percentile according to World Health Organization (WHO) Child Growth Standards. If 16 to 25 years of age: has a BMI of 15 to 35 kilograms (kg)/square meter (m^2).
  • For female participants of childbearing potential: negative pregnancy test, adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to Day 1, agreement to continue adequate contraception through 3 months following vaccine administration.

Who cannot join

  • Has a history of a diagnosis or condition that, in the judgment of Investigator, is clinically unstable or may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures. Clinically unstable is defined as diagnosis or condition requiring significant changes in management or medication within the 2 months prior to Screening and includes ongoing workup of an undiagnosed illness that could lead to a new diagnosis or condition.
  • Has received, or plans to receive, any nonstudy vaccine < 28 days prior to or after any study injection.
  • Has a screening liver function test (aspartate aminotransferase, alanine aminotransferase, total bilirubin) or a screening creatinine result of Toxicity Grade ≥1.
  • Has a Screening hematology or coagulation result of Toxicity Grade ≥1.
  • Is acutely ill or febrile (body temperature ≥38.0 degrees Celsius [°C]/100.4 degrees Fahrenheit [°F]) at the Screening Visit.
  • Has received systemic immunosuppressants or immune-modifying drugs for > 14 days in total within 6 months prior to the day of enrollment (for corticosteroids, ≥1 milligrams (mg)/kg/day or ≥10 mg/day prednisone equivalent).
Show all 14Show fewer
  • Has received an antiviral with activity against CMV (ganciclovir, valganciclovir, foscarnet, cidofovir, letermovir, acyclovir, valacyclovir) <2 weeks prior to the day of the first study injection (Day 1) or plans to do so during the course of the study.
  • Reports a history of myocarditis, pericarditis, or myopericarditis.
  • Has reported medical history of hepatitis B, hepatitis C, or human immunodeficiency virus (HIV); or a positive screening test for hepatitis B surface antigen (HBsAg), hepatitis C antibodies, or HIV 1 or 2 antibodies.
  • Has previously received an investigational CMV vaccine.
  • Has received systemic immunoglobulins or blood products <3 months prior to the day of the first study injection (Day 1).
  • Has donated ≥ 450 milliliter (mL) of blood products <28 days prior to the day of the first study injection (Day 1).
  • Has participated in an interventional clinical study <28 days prior to the day of the first study injection (Day 1) or plans to do so while enrolled in the study.
  • Note: Other inclusion and exclusion criteria may apply.

Trial locations and contacts

57 sites in 3 countries.

57 sites in 3 countries

United States44 sites

  • Albuquerque Clinical Trials Inc - Clinedge - PPDS

    Albuquerque, New Mexico, 87102-2619

  • Velocity Clinical Research -Albuquerque -PPDS

    Albuquerque, New Mexico, 87102-3644

  • Children's Healthcare of Atlanta

    Atlanta, Georgia, 30322-1014

  • Tekton Research - Texas - PPDS

    Austin, Texas, 78705

  • University of Maryland School of Medicine

    Baltimore, Maryland, 21201-1509

  • Tekton Research - Beaumont - Platinum - PPDS

    Beaumont, Texas, 77706-3061

  • Velocity Clinical Research (Binghamton - New York) - PPDS

    Binghamton, New York, 13901-1046

  • OnSite Clinical Solutions, LLC - ClinEdge - PPDS

    Charlotte, North Carolina, 28277-4859

  • The Pediatric Centre

    Columbia, Maryland, 21045

  • Benchmark Research - Covington - HyperCore- PPDS

    Covington, Louisiana, 70433

  • iResearch Atlanta - CenExel - PPDS

    Decatur, Georgia, 30030-3438

  • Wayne State University

    Detroit, Michigan, 48201

  • Prohealth Research Center

    Doral, Florida, 33166-6613

  • Tekton Research - Oklahoma- PPDS

    Edmond, Oklahoma, 73013

  • Tekton Research - Fort Collins - Platinum - PPDS

    Fort Collins, Colorado, 80525-5752

  • Benchmark Research - Fort Worth - HyperCore -PPDS

    Fort Worth, Texas, 76135

  • The Pediatric Centre of Frederick

    Frederick, Maryland, 21702

  • University of Texas Medical Branch (UTMB)

    Galveston, Texas, 77550

  • Velocity Clinical Research - Gulfport

    Gulfport, Mississippi, 39503

  • West Houston Clinical Research - Hunt - PPDS

    Houston, Texas, 77055-1626

  • Clinical Research Prime - ClinEdge - PPDS

    Idaho Falls, Idaho, 83404-5305

  • University of Florida Jacksonville

    Jacksonville, Florida, 32209

  • Paradigm Clinical Research Institute Inc - ClinEdge - PPDS

    La Mesa, California, 91942-3189

  • Velocity Clinical Research - San Diego - PPDS

    La Mesa, California, 91942

  • Velocity Clinical Research (Lincoln-Nebraska) - PPDS

    Lincoln, Nebraska, 68510

  • Velocity Clinical Research - Medford - PPDS

    Medford, Oregon, 97504-7738

  • University of Minnesota

    Minneapolis, Minnesota, 55455

  • Meharry Medical College

    Nashville, Tennessee, 37208

  • Tulane Medical Center

    New Orleans, Louisiana, 70112-2632

  • Velocity Clinical Research (Norfolk - Nebraska) - PPDS

    Norfolk, Nebraska, 68701-7701

  • Lynn Institute of Norman - ERN - PPDS

    Norman, Oklahoma, 73072-3251

  • Velocity Clinical Research (Omaha-Nebraska) - Platinum - PPDS

    Omaha, Nebraska, 68134-3664

  • Clinical Neurosciences Solutions Inc. (Orlando-East South St)

    Orlando, Florida, 32801-2987

  • Victoria Clinical Research Group

    Port Lavaca, Texas, 77979

  • Rochester Clinical Research, Inc

    Rochester, New York, 14609-3173

  • Benchmark Research - Sacramento -Hypercore- PPDS

    Sacramento, California, 95864

  • JBR Clinical Research - CenExel JBR - PPDS

    Salt Lake City, Utah, 84107-4536

  • Benchmark Research - San Angelo - HyperCore - PPDS

    San Angelo, Texas, 76904

  • Tekton Research - Texas - Platinum - PPDS

    San Antonio, Texas, 78229

  • Palm Harbor Dermatology

    Tampa, Florida, 33609-2230

  • Santos Research Center

    Tampa, Florida, 33615-3219

  • DM Clinical Research - ERN- PPDS

    Tomball, Texas, 77375

  • Crossroads Clinical Research (Victoria)

    Victoria, Texas, 77901

  • Velocity Clinical Research (Washington)- PPDS

    Washington D.C., District of Columbia, 20016

Other trials in United States

Canada7 sites

  • M.A.G.I.C. Clinic Ltd. Metabolics and Genetics in Calgary

    Calgary, Alberta

  • ALTA Clinical Research Inc

    Edmonton, Alberta

  • Canadian Center for Vaccinology

    Halifax, Nova Scotia

  • Hamilton Medical Research Group

    Hamilton, Ontario

  • Centre Hospitalier Universitaire Sainte-Justine

    Montreal, Quebec

  • CARe Clinic

    Red Deer, Alberta

  • Bluewater Clinical Research Group

    Sarnia, Ontario

Other trials in Canada

United Kingdom6 sites

  • Queen Elizabeth Hospital

    Birmingham

  • Noah's Ark Children's Hospital for Wales

    Cardiff

  • Lakeside Healthcare

    Corby, Northamptonshire

  • St. George Hospital

    London

  • Sheffield Children's Hospital

    Sheffield, South Yorkshire

  • Southampton General Hospital

    Southampton, Hampshire

Other trials in United Kingdom

About this study

Official title: A Phase 1/2a Open-Label Dose-Ranging and Observer-Blind Placebo-Controlled, Safety and Immunogenicity Study of mRNA-1647 Cytomegalovirus Vaccine in Female and Male Participants 9 to 15 Years of Age and Participants 16 to 25 Years of Age

The main purpose of study is to evaluate the safety and immunogenicity of different dose levels of mRNA-1647 versus control in healthy cytomegalovirus (CMV)-seronegative and CMV-seropositive female and male participants 9 to 15 years of age. In addition, mRNA-1647 will be evaluated in female participants 16 to 25 years as a comparator cohort.

Read the detailed description

The study will be conducted in 2 parts: Part 1 Dose-Ranging and Part 2 Safety Expansion.

Conditions
Cytomegalovirus
Being tested
mRNA-1647, Placebo
Keywords
mRNA-1647 Vaccine, CMV, Moderna

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • mRNA-1647Biological

    Sterile liquid for injection

  • PlaceboOther

    0.9% sodium chloride injection (normal saline)

Study groups in NCT05575492
Study groupRoleWhat they receive
mRNA-1647 Dose AExperimentalCMV-seronegative or CMV-seropositive participants 9 to 15 years of age will receive mRNA-1647 at Dose Level A by intramuscular (IM) injection given as a 3-injection series on Day 1, Month 2, and Month 6.
Receives: Biological: mRNA-1647
mRNA-1647 Dose BExperimentalCMV-seronegative or CMV-seropositive participants 9 to 15 years of age will receive mRNA-1647 at Dose Level B by IM injection given as a 3-injection series on Day 1, Month 2, and Month 6.
Receives: Biological: mRNA-1647
mRNA-1647 Dose CExperimentalCMV-seronegative or CMV-seropositive participants 9 to 15 years of age and 16 to 25 years of age will receive mRNA-1647 at Dose Level C by IM injection given as a 3-injection series on Day 1, Month 2, and Month 6.
Receives: Biological: mRNA-1647
Dose Expansion: mRNA-1647 (3-dose Schedule)ExperimentalCMV-seronegative or CMV-seropositive participants 9 to 15 years of age will receive mRNA-1647 at selected dose level by IM injection given as a 3-injection series on Day 1, Month 2, and Month 6.
Receives: Biological: mRNA-1647
Dose Expansion: mRNA-1647 (2-dose Schedule)ExperimentalCMV-seronegative participants 9 to 15 years of age will receive mRNA-1647 at selected dose level by IM injection given as a 2-injection series on Day 1 and Month 6.
Receives: Biological: mRNA-1647
Dose Expansion: Placebo (3-dose Schedule)Placebo comparatorCMV-seronegative or CMV-seropositive participants 9 to 15 years of age will receive placebo by IM injection given as a 3-injection series on Day 1, Month 2, and Month 6.
Receives: Other: Placebo
Dose Expansion: Placebo (2-dose Schedule)Placebo comparatorCMV-seronegative participants 9 to 15 years of age will receive placebo by IM injection given as a 2-injection series on Day 1 and Month 6.
Receives: Other: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Number of Solicited Local and Systemic Reactogenicity Adverse Reactions (ARs)

    Measured: Up to Day 176 (7 days after each study injection)

  2. Number of Unsolicited Adverse Events (AEs)

    Measured: Up to Day 197 (28 days after each study injection)

  3. Number of Medically Attended Adverse Events (MAAEs)

    Measured: Up to Day 347 (6 months after the last study injection)

  4. Number of Serious Adverse Events (SAEs), Adverse Events of Special Interest (AESIs), and AEs Leading to Discontinuation

    Measured: Up to Day 527 (end of study)

  5. Geometric Mean Titer (GMT) of Anti-CMV Neutralizing Antibodies (nAbs)

    Serum functional antibody levels against vaccine antigens will be measured by nAb titer against epithelial cell infection and nAb titer against fibroblast infection.

    Measured: Up to Day 527 (end of study)

  6. Geometric Mean Fold-Rise (GMFR) of Anti-CMV nAbs

    Serum functional antibody levels against vaccine antigens will be measured by nAb titer against epithelial cell infection and nAb titer against fibroblast infection.

    Measured: Up to Day 527 (end of study)

  7. Number of Participants with ≥2-Fold, 3-Fold, and 4-Fold increases Over Baseline of Anti-CMV Antibodies

    Serum functional antibody levels against vaccine antigens will be measured by nAb titer against epithelial cell infection and nAb titer against fibroblast infection.

    Measured: Up to Day 527 (end of study)

Secondary outcomes (3)

  1. Geometric Mean Concentration (GMC) of Binding Anti-Glycoprotein B (gB) Specific Immunoglobulin G (IgG) and Anti-Pentamer Specific IgG

    Serum antigen-specific binding antibody titers against vaccine antigens will be measured by enzyme-linked immunosorbent assay (ELISA) specific to the gB and pentamer proteins.

    Measured: Up to Day 527 (end of study)

  2. Number of Participants with ≥2-Fold, 3-Fold, and 4-Fold Increases Over Baseline of Binding Anti-gB and Anti-pentamer Specific IgG

    Serum antigen-specific binding antibody titers against vaccine antigens will be measured by ELISA specific to the gB and pentamer proteins.

    Measured: Up to Day 527 (end of study)

  3. GMFR of Binding Anti-gB and Anti-pentamer Specific IgG

    Serum antigen-specific binding antibody concentrations against vaccine antigens will be measured by ELISA specific to the gB and pentamer proteins.

    Measured: Up to Day 527 (end of study)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted12 Oct 2022
  2. Study start7 Nov 2022
  3. Primary completion12 May 2026
  4. Study completion12 May 2026

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1/2
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Sequential
Model description
Part 1: Dose-escalating, non-randomized Part 2: Randomized
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
873 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05575492
Sponsor's protocol ID
mRNA-1647-P104
Other IDs
2022-001545-20
Status last verified
May 2026
First submitted
7 Oct 2022
Last updated
4 Jun 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing mRNA-1647 in people with Cytomegalovirus, run by ModernaTX, Inc. at 57 sites in 3 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 14 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 4 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 57 sites in United States, Canada, United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of Solicited Local and Systemic Reactogenicity Adverse Reactions (ARs) (time frame: Up to Day 176 (7 days after each study injection)). The study lists 7 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05575492.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 4 Jun 2026.

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