NCT04975893

Brief Summary

The main purpose of the extension phase of this study is to evaluate the longer-term immune persistence of mRNA-1647 vaccine administered to CMV-seronegative and CMV-seropositive adults who completed Study mRNA-1647-P202 (NCT04232280). For participants in the optional booster phase (BP), the main purpose is to evaluate the long-term immunogenicity and safety of the mRNA-1647 vaccine in both participants receiving a booster dose (BD) and those not receiving a BD, and to additionally evaluate the reactogenicity in participants receiving a BD.

Trial Health

87
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
135

participants targeted

Target at P75+ for phase_2

Timeline
Completed

Started Jun 2021

Typical duration for phase_2

Geographic Reach
1 country

7 active sites

Status
completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

Study Start

First participant enrolled

June 18, 2021

Completed
21 days until next milestone

First Submitted

Initial submission to the registry

July 9, 2021

Completed
17 days until next milestone

First Posted

Study publicly available on registry

July 26, 2021

Completed
4.5 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

January 19, 2026

Completed
Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

January 19, 2026

Completed
Last Updated

February 2, 2026

Status Verified

January 1, 2026

Enrollment Period

4.6 years

First QC Date

July 9, 2021

Last Update Submit

January 30, 2026

Conditions

Cytomegalovirus Infection

Keywords

ModernamRNA-1647CytomegalovirusCMVCytomegalovirus VaccineCytomegalovirus InfectionsCytomegalovirus CongenitalVirus DiseasesInfection ViralDNA Virus InfectionsMessenger RNA

Outcome Measures

Primary Outcomes (6)

  • Primary Extension Phase: Geometric Mean Titers (GMTs) of Antigen-Specific Neutralizing Antibody (nAb) and Binding Antibody (bAb)

    Up to 3 years

  • BP: GMTs of Antigen-Specific nAb and bAb

    BP Month 0, BP Month 1, BP Month 3, BP Month 6, and BP Month 12

  • BP: Number of Participants with Solicited Adverse Reactions (ARs)

    Up to BP Day 7 (7 days after BP vaccination)

  • BP: Number of Participants with Unsolicited Adverse Events (AEs)

    Up to BP Day 28 (28 days after BP vaccination)

  • BP: Number of Participants with Medically-Attended AEs (MAAEs)

    Up to BP Month 6 (6 months after BP vaccination)

  • BP: Number of Participants with Adverse Events of Special Interest (AESIs), Serious Adverse Events (SAEs), and AEs Leading to Discontinuation of Study

    Up to BP Month 12

Secondary Outcomes (2)

  • Primary Extension Phase: Number of Participants With AEs Leading to Study Discontinuation

    Up to 3 years

  • Primary Extension Phase: Number of Participants With SAEs

    Up to 3 years

Study Arms (3)

Primary Extension Phase

OTHER

CMV-seropositive and CMV-seronegative participants who completed Study mRNA-1647-P202 will be followed every 6 months for 3 years in this study after the final visit in Study mRNA-1647-P202.

Biological: mRNA-1647

Optional Booster Phase - BD Recipients

EXPERIMENTAL

Participants who opted to enroll into the optional Booster Phase will receive a single mRNA-1647 vaccine dose.

Other: mRNA-1647

Optional Booster Phase - Observational Group

OTHER

Participants who opted to enroll into the Observational Group will be followed in the optional BP until BP Month 12.

Biological: mRNA-1647

Interventions

mRNA-1647BIOLOGICAL

No investigational product will be administered during the Primary Extension Phase or to the participants in the Observational Group.

Optional Booster Phase - Observational GroupPrimary Extension Phase

Eligibility Criteria

Age18 Years - 40 Years
Sexall
Healthy VolunteersNo
Age GroupsAdult (18-64)

You may qualify if:

  • Primary Extension Phase:
  • Male and female participants who were CMV-seronegative at the Study mRNA-1647-P202 Screening visit, completed the final Study mRNA-1647-P202 visit, and remained CMV-seronegative at Screening for Study mRNA-1647-P202-EXT.
  • Male and female participants who were CMV-seropositive at the Study mRNA-1647-P202 Screening visit, were randomized to receive mRNA-1647 injection (and not placebo), and completed the final visit in Study mRNA-1647-P202.
  • Understands and agrees to comply with the trial procedures and provides written informed consent.
  • According to the assessment of the Investigator, is in good general health and is capable of complying with trial procedures.
  • Optional Booster Phase:
  • For BD Recipients:
  • \- CMV-seronegative and CMV-seropositive participants who received mRNA-1647 medium dose injection (and not placebo or other dose levels) in Study mRNA-1647-P202, including participants who enrolled in the Primary Extension Phase of Study mRNA-1647-P202-EXT and participants who were eligible but did not previously enroll in the Primary Extension Phase of Study mRNA-1647-P202-EXT are eligible to receive a BD in the optional BP.
  • For Observational Group:
  • \- CMV-seronegative and CMV-seropositive participants who received mRNA-1647 low dose or high dose injection (and not placebo or mRNA-1647 medium dose injection) in Study mRNA-1647-P202, including participants who enrolled in the Primary Extension Phase of Study mRNA-1647-P202-EXT and participants who were eligible but did not previously enroll in the Primary Extension Phase of Study mRNA-1647-P202-EXT are eligible to enroll in the observational group.

You may not qualify if:

  • Primary Extension Phase:
  • Receipt of any CMV vaccine other than mRNA-1647.
  • Diagnosis or condition that, in the judgment of the Investigator, may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to trial procedures, including any medical, psychiatric, or occupational condition that, in the opinion of the Investigator, might pose additional risk due to participation in the study or could interfere with the interpretation of study results.
  • Optional Booster Phase:
  • For BD Recipients:
  • \- Participants from the placebo, mRNA-1647 low dose, or mRNA-1647 medium dose groups in Study mRNA-1647-P202.
  • For Observational Group:
  • \- Participants from the placebo or mRNA-1647 medium dose groups in study mRNA-1647-P202.

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (7)

Optimal Research, LLC

Peoria, Illinois, 61610, United States

Location

Johnson County Clin-Trials, Inc.

Lenexa, Kansas, 66219, United States

Location

Alliance for Multispeciality Research, LLC

Lexington, Kentucky, 40509, United States

Location

Tekton Research Inc

Austin, Texas, 78745, United States

Location

Crossroads Clinical Research (Victoria)

Victoria, Texas, 77901, United States

Location

J. Lewis Research, Inc. / Foothill Family Clinic South

Salt Lake City, Utah, 84109, United States

Location

J. Lewis Research, Inc. / Foothill Family Clinic South

Salt Lake City, Utah, 84121, United States

Location

MeSH Terms

Conditions

Cytomegalovirus InfectionsVirus DiseasesDNA Virus Infections

Interventions

mRNA-1647 cytomegalovirus vaccine

Condition Hierarchy (Ancestors)

Herpesviridae InfectionsInfections

Study Design

Study Type
interventional
Phase
phase 2
Allocation
NON RANDOMIZED
Masking
NONE
Purpose
PREVENTION
Intervention Model
SEQUENTIAL
Sponsor Type
INDUSTRY
Responsible Party
SPONSOR

Study Record Dates

First Submitted

July 9, 2021

First Posted

July 26, 2021

Study Start

June 18, 2021

Primary Completion

January 19, 2026

Study Completion

January 19, 2026

Last Updated

February 2, 2026

Record last verified: 2026-01

Locations

US(7)