A Study to Evaluate the Efficacy, Safety, and Immunogenicity of mRNA-1647 Cytomegalovirus (CMV) Vaccine in Healthy Participants 16 to 40 Years of Age
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ClinicalTrials.gov Identifier: NCT05085366 |
Recruitment Status :
Recruiting
First Posted : October 20, 2021
Last Update Posted : May 27, 2022
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Condition or disease | Intervention/treatment | Phase |
---|---|---|
Cytomegalovirus Infection | Biological: mRNA-1647 Biological: Placebo | Phase 3 |
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 6900 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor) |
Masking Description: | Observer-blind |
Primary Purpose: | Prevention |
Official Title: | A Phase 3, Randomized, Observer-Blind, Placebo-Controlled Study to Evaluate the Efficacy, Safety, and Immunogenicity of mRNA-1647 Cytomegalovirus (CMV) Vaccine in Healthy Participants 16 to 40 Years of Age |
Actual Study Start Date : | October 26, 2021 |
Estimated Primary Completion Date : | January 29, 2023 |
Estimated Study Completion Date : | July 29, 2025 |

Arm | Intervention/treatment |
---|---|
Experimental: mRNA-1647
Participants will receive mRNA-1647 vaccine by intramuscular (IM) injection on Day 1, Day 57, and Day 169.
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Biological: mRNA-1647
Lyophilized product that is reconstituted with 0.9% sodium chloride (normal saline) |
Placebo Comparator: Placebo
Participants will receive mRNA-1647 vaccine matching placebo by IM injection on Day 1, Day 57, and Day 169.
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Biological: Placebo
0.9% sodium chloride (normal saline) injection |
- Seroconversion From a Negative to a Positive Result for Serum Immunoglobulin G (IgG) Against Antigens not Encoded by mRNA-1647 [ Time Frame: Day 197 (28 days after the third injection) up to Day 887 (24 months after the third injection) ]
- Number of Participants With Solicited Adverse Reactions (ARs) [ Time Frame: Up to 176 days (7 days after each injection) ]
- Number of Participants With Unsolicited Adverse Events (AEs) [ Time Frame: Up to 197 days (28 days after each injection) ]
- Number of Participants With Medically-Attended Adverse Events (MAAEs) [ Time Frame: Day 1 through 6 months after the last injection (up to 347 days) ]
- Number of Participants With Adverse Event of Special Interests (AESIs) and Serious Adverse Events (SAEs) [ Time Frame: Day 1 through end of study (up to Day 887) ]
- Geometric Mean Titers (GMTs) of Antigen-Specific Neutralizing Antibody (nAb) and Binding Antibody [ Time Frame: Day 1, Months 3, 7, 12, 18, 24, and 30 ]

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.
Ages Eligible for Study: | 16 Years to 40 Years (Child, Adult) |
Sexes Eligible for Study: | Female |
Accepts Healthy Volunteers: | Yes |
Key Inclusion Criteria:
- Participants aged ≥20 years, has or anticipates having direct exposure (in the home, socially, or occupationally) to at least 1 child ≤5 years of age. Direct exposure is defined as either participant is the parent, or participant has close contact (feeding, diaper changes, childcare/supervision) for at least 8 hours per week.
- CMV-seronegative Cohort is CMV-seronegative based on CMV testing at Screening.
- CMV-seropositive Cohort is CMV-seropositive based on CMV testing at Screening.
- Investigator assessment confirms that the participant (including in the case of an emancipated minor), or parent(s)/legally acceptable representative (LAR)(s), as applicable, understand and are willing and physically able to comply with protocol-mandated follow-up including all study visits and procedures anticipated during the 30 month study period.
- Has a body mass index of 15-35 kilograms (kg)/square meter (m^2), inclusive.
- Female participants: Urine pregnancy test is negative at Screening and negative on the day of the first injection (Day 1). If the participant is sexually active, has practiced adequate contraception for at least 28 days prior to the first injection (Day 1) and agrees to continue adequate contraception through 3 months following the third study injection (Month 9/Day 257).
Key Exclusion Criteria:
- Female participant is of non-childbearing potential.
- History of a diagnosis or condition that, in the judgment of the Investigator, is clinically unstable or may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures.
- Received or plans to receive any nonstudy vaccine <28 days prior to any study injection; in addition, the following criteria for COVID-19 and influenza vaccines apply:
- Any Coronavirus disease 2019 (COVID-19) vaccination series must have been completed a minimum 28 days prior to receiving any dose of the study injection.
- COVID-19 vaccines (regardless of manufacturer) must be administered at least 28 days prior to or after any study injection.
- Influenza vaccines may be administered > 14 days prior to or after any study injection.
- Received systemic immunosuppressants or immune-modifying drugs for >14 days in total within 6 months prior to the day of first injection (Day 1) (for corticosteroids, ≥5 milligrams (mg)/day of prednisone equivalent) or plans to do so during the course of the study. Inhaled, nasal, and topical steroids are allowed.
- Receipt of an antiviral with activity against CMV (ganciclovir, valganciclovir, foscarnet, cidofovir, letermovir, acyclovir, valacyclovir) <2 weeks prior to the day of first injection or plans to do so during the course of the study.
- Previous receipt of an investigational CMV vaccine.
- Receipt of systemic immunoglobulins or blood products <3 months prior to the day of first injection.
- Participated in an interventional clinical study <28 days prior to the day of first injection (Day 1) or plans to do so while enrolled in this study.
- Participant has donated ≥450 milliliters (mL) of blood products <28 days prior to Screening.
- Participant is a member of study team or is an immediate family member or household member of study personnel.

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT05085366
Contact: Moderna Clinical Trials Support Center | 1-877-777-7187 | clinicaltrials@modernatx.com |

Responsible Party: | ModernaTX, Inc. |
ClinicalTrials.gov Identifier: | NCT05085366 |
Other Study ID Numbers: |
mRNA-1647-P301 2020-006051-17 ( EudraCT Number ) |
First Posted: | October 20, 2021 Key Record Dates |
Last Update Posted: | May 27, 2022 |
Last Verified: | May 2022 |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
mRNA-1647 Moderna Cytomegalovirus CMV Cytomegalovirus Vaccine Cytomegalovirus Infections |
Cytomegalovirus Congenital Virus Diseases Infection Viral DNA Virus Infections Messenger RNA |
Infections Cytomegalovirus Infections Herpesviridae Infections DNA Virus Infections Virus Diseases |