Dose-Finding Trial to Evaluate the Safety and Immunogenicity of Cytomegalovirus (CMV) Vaccine mRNA-1647 in Healthy Adults

Study at a glance

From the registry record, last updated by the sponsor on 5 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title

A Phase 2, Randomized, Observer-Blind, Placebo-Controlled, Dose-Finding Trial to Evaluate the Safety and Immunogenicity of Cytomegalovirus Vaccine mRNA-1647 in Healthy Adults

ClinicalTrials.gov ID

NCT04232280

Acronym / sponsor ID

mRNA-1647-P202

Conditions

Cytomegalovirus Infection

Keywords

Moderna, mRNA-1647, Cytomegalovirus, CMV, Cytomegalovirus Vaccine, Cytomegalovirus Infections, Cytomegalovirus Congenital, Virus Diseases

Phase

Phase 2

Study type

Interventional

Recruitment status

Completed

Enrolment

315 participants (actual)

Lead sponsor

ModernaTX, Inc.Industry (pharma, biotech, devices)

Study start

9 Jan 2020 (actual)

Primary completion

4 Jan 2023 (actual)

Study completion

4 Jan 2023 (actual)

First posted

18 Jan 2020 (actual)

Results

Posted 5 May 2026

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Study design

Primary purpose

Prevention

Allocation

Randomised

Intervention model

Sequential

Masking

Double blind (participant, investigator)

Number of arms

4

Who may qualify

Ages

18 to 40 years

Sex

All

Healthy volunteers

Accepted

Age groups

Adult

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Primary outcome

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

   Time frame: Up to Day 175 (7 days following last dose administration)

   Solicited ARs were selected signs and symptoms occurring after vaccination administration during a specified post-vaccination follow-up period. The occurrence and intensity of the selected signs and symptoms was actively solicited from the participant during a specified post-vaccination follow-up period (day of vaccination and 6 subsequent days), using a predefined checklist in the electronic diary. The following local ARs were solicited: pain at injection site, erythema (redness) at injection site, swelling/induration (hardness) at injection site, and localized axillary swelling or tenderness ipsilateral to the vaccination arm. The following systemic ARs were solicited: headache, fatigue, myalgia (muscle aches all over the body), arthralgia (aching in several joints), nausea/vomiting, rash, fever, and chills. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

2. Number of Participants With Unsolicited Adverse Events (AEs)

   Time frame: Up to Day 196 (28 days following last dose administration)

   An unsolicited AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. The treatment-emergent AEs are defined as any event not present before exposure to study drug or any event already present that worsened in intensity or frequency after exposure. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section."

3. Number of Participants With Medically Attended Adverse Events (MAAEs)

   Time frame: Up to Day 336 (6 months following last dose administration)

   An MAAE is an AE that lead to a visit to a healthcare practitioner (HCP). This would include visits to study clinic for unscheduled assessments (for example, rash assessment, abnormal laboratory follow-up), and visits to HCPs external to the clinical site (for example, urgent care, primary care physician). A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section."

4. Number of Participants With Serious Adverse Events (SAEs)

   Time frame: Up to Day 504 (1 year following last dose administration)

   An SAE was defined as any untoward medical occurrence that, in the view of either the Investigator or the Sponsor, resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization (hospitalization or prolongation of hospitalization in the absence of a precipitating event was not in itself an SAE), resulted in persistent disability/incapacity, was a congenital anomaly/birth defect, or was a medically important event. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section."

5. Geometric Mean Titer (GMT) of Serum Neutralizing Anti-CMV Antibodies Against Epithelial Cell Infection and Against Fibroblast Infection

   Time frame: Baseline (Day 1), Day 29, Day 56, Day 84, Day 168, Day 196, Day 336, Day 504

   Blood samples for antibody-mediated immunogenicity (AMI) analysis were collected during protocol-specified study visits. Serological assessment of serum anti-CMV neutralizing antibody titers against epithelial cell infection and fibroblast infection were measured by a neutralization assay. Results are reported as fold dilution (titer). GMT 95% confidence interval (CI) was calculated based on the t-distribution of the log-transformed values then back transformed to the original scale for presentation.

6. Geometric Mean Ratio (GMR) of Serum Neutralizing Anti-CMV Antibodies Against Epithelial Cell Infection and Against Fibroblast Infection

   Time frame: Day 29, Day 56, Day 84, Day 168, Day 196, Day 336, Day 504

   Blood samples for antibody-mediated immunogenicity analysis were collected during protocol-specified study visits. Serological assessment of serum anti-CMV neutralizing antibody titers against epithelial cell infection and fibroblast infection were measured by a neutralization assay. The GMR measures the changes in immunogenicity titers within participants. Results are reported as a ratio (post-baseline/baseline titers). GMR 95% CI was calculated based on the t-distribution of the log-transformed values then back transformed to the original scale for presentation.

7. Percentage of Participants With ≥2-Fold, 3-Fold, and 4-Fold Increases in Neutralizing Antibodies (nAb) Over Baseline Against Epithelial Cell Infection and Against Fibroblast Infection

   Time frame: Day 29, Day 56, Day 84, Day 168, Day 196, Day 336, Day 504

   Blood samples for antibody-mediated immunogenicity analysis were collected during protocol-specified study visits. Serological assessment of serum anti-CMV nAb titers against epithelial cell infection and fibroblast infection were measured by a neutralization assay. A ≥z-fold increase from baseline at participant level was defined as a ≥z * the lower limit of quantification (LLOQ) for participants with baseline antibody level below the LLOQ, or a z-times or higher-level ratio in participants with baseline antibody level equal to or above the LLOQ. LLOQ=16. Results are reported as percentage of participants with ≥2-fold, 3-fold, and 4-fold increases in serum anti-CMV nAb titers from baseline. 95% CI for percentage is calculated using the Clopper-Pearson method.

Results and safety

Loading the posted results from ClinicalTrials.gov…

Research links

• Official record on ClinicalTrials.govLast updated by the sponsor 5 May 2026.
• Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
• Derived from this study: PubMed 38190492Galiza EP, Khalil A, Heath PT. Update on Vaccines in Antenatal Care. Pediatr Infect Dis J. 2024 Feb 1;43(2):e60-e62. doi: 10.1097/INF.0000000000004183. Epub 2023 Dec 27. No abstract available.
• Individual participant dataSharing planned: No

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

The record lists no contact. Use the official record to reach the sponsor.

9 sites in 1 country: see every site and its status.