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A Study to Evaluate the Efficacy, Safety, and Immunogenicity of mRNA-1647 Cytomegalovirus (CMV) Vaccine in Healthy Participants 16 to 40 Years of Age

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

Status
Terminated
Phases
Phase 3
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT05085366
Enrollment
7454
Registered
2021-10-20
Start date
2021-10-26
Completion date
2025-11-04
Last updated
2025-12-15

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Cytomegalovirus Infection

Keywords

mRNA-1647, Moderna, Cytomegalovirus, CMV, Cytomegalovirus Vaccine, Cytomegalovirus Infections, Cytomegalovirus Congenital, Virus Diseases, Infection Viral, DNA Virus Infections, Messenger RNA

Brief summary

The main purpose of this study is to evaluate the efficacy of mRNA 1647 vaccine in CMV-seronegative female participants and to evaluate the safety and reactogenicity of mRNA-1647 vaccine in all participants. The purpose of the Phase 3 extension substudy is to extend the observation period of the main study and to assess the longer-term immunogenicity, efficacy, and safety of the mRNA-1647 vaccine against primary CMV infection in healthy females who were CMV-seronegative at Baseline of the mRNA-1647-P301 main study (including participants who remain CMV-seronegative upon entry into the extension substudy and participants who seroconverted during the main study). The extension substudy will also evaluate the immune persistence and safety of mRNA-1647 in a subset of female participants who were CMV-seropositive at Baseline of the main study. No interventional vaccine will be administered in the extension substudy.

Interventions

BIOLOGICALmRNA-1647

Lyophilized product that is reconstituted with 0.9% sodium chloride (normal saline)

BIOLOGICALPlacebo

0.9% sodium chloride (normal saline) injection

Sponsors

ModernaTX, Inc.
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Masking description

Observer-blind

Eligibility

Sex/Gender
FEMALE
Age
16 Years to 40 Years
Healthy volunteers
Yes

Inclusion criteria

Key Inclusion Criteria: * Participants aged ≥20 years, has or anticipates having direct exposure within 7 months after the planned first dose (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. * Female participants of child-bearing potential: Urine pregnancy test is negative at Screening and negative on the day of the first injection (Day 1). If the participant is sexually active with men, has practiced adequate contraception or has abstained from all activities that could result in pregnancy 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). Extension substudy: * All consenting participants who were CMV-seronegative at Baseline in the mRNA-1647-P301 main study (including those who did seroconvert and did not seroconvert during the main study), received at least one study injection in the main study but did not withdraw study consent, and completed the final study visit in mRNA-1647-P301 main study. * Consenting participants in mRNA-1647-P301 main study who were CMV-seropositive at Baseline, received all 3 study injections, did not withdraw study consent, and completed the final study visit in the main study. Key

Exclusion criteria

* 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 and after any study injection; in addition, the following criteria for COVID-19 and influenza vaccines apply: * Any COVID-19 primary vaccination series must have been completed a minimum 28 days prior to receiving any dose of the study injection. * COVID-19 vaccines (including any booster dose, 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. Stable immunomodulator regimens used for managing environmental allergies 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. Extension substudy: * 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 study 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.

Design outcomes

Primary

MeasureTime frame
Number of Participants With Systemic Viral DisseminationMonth 30 up to Month 54
Number of Participants With Unsolicited Adverse Events (AEs)Up to 197 days (28 days after each injection)
Number of Participants With Medically-Attended Adverse Events (MAAEs)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)Day 1 through Month 30
Geometric Mean Titers (GMTs) of Antigen-Specific Neutralizing Antibody (nAb)Month 30 up to Month 54
Geometric Mean Concentration (GMC) of Binding AntibodyMonth 30 up to Month 54
Seroconversion From a Negative to a Positive Result for Serum IgG Against Antigens not Encoded by mRNA-1647Month 30 up to Month 54
Seroconversion From a Negative to a Positive Result for Serum Immunoglobulin G (IgG) Against Antigens not Encoded by mRNA-1647Day 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)Up to 176 days (7 days after each injection)

Secondary

MeasureTime frame
GMC of Antigen-Specific Binding AntibodyDay 1, Months 3, 7, 12, 18, 24, and 30
Number of Participants with AEs leading to Study Discontinuation, SAEs and DeathsMonth 30 up to Month 54
Number of Participants With Systemic Viral DisseminationDay 1 through Month 30
Number of Participants With Positive Urine CMV Polymerase Chain Reaction (PCR) Results Post SeroconversionDay 1 through Month 30
Number of Participants With Positive Urine CMV PCR Results Post SeroconversionMonth 30 up to Month 54
GMTs of Antigen-Specific nAbDay 1, Months 3, 7, 12, 18, 24, and 30

Countries

Australia, Belgium, Canada, Estonia, Finland, France, Germany, Israel, Italy, Japan, Spain, United Kingdom, United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 11, 2026