Moderna's CMV vaccine shows promise in Long-Term Follow-Up study
NCT ID NCT04975893
First seen Jun 26, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This study is a long-term follow-up of a phase 2 trial testing Moderna's mRNA-1647 vaccine against cytomegalovirus (CMV). It involves 135 adults who previously received the vaccine or a placebo. Researchers are checking how long the immune response lasts and whether a booster dose is safe and effective. The goal is to eventually prevent CMV infection, which can be dangerous for pregnant women and people with weak immune systems.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- mRNA-1647 vaccine
- What this could lead to
- If successful, this could support the development of a vaccine to prevent cytomegalovirus (CMV) infection, which can cause serious complications in newborns and people with weakened immune systems.
- What could go wrong
- This is a small, early-phase extension study focused on long-term immune persistence and safety, not on proving the vaccine prevents infection. The results may not confirm effectiveness, and side effects are still being evaluated.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
-
Phase 2
Tests whether the treatment actually works, and watches for side effects, in a larger group.
- Participants
-
135 people
The number who actually took part.
- Started
-
Jun 2021
- Finished
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Jan 2026
- Lead sponsor
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A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
-
18 to 40 years
- Sex
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Anyone
- Healthy volunteers
-
Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 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. Exclusion Criteria: 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. Note: Other protocol-defined inclusion/exclusion criteria apply
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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Alliance for Multispeciality Research, LLC
Lexington, Kentucky, 40509, United States
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Crossroads Clinical Research (Victoria)
Victoria, Texas, 77901, United States
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J. Lewis Research, Inc. / Foothill Family Clinic South
Salt Lake City, Utah, 84109, United States
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J. Lewis Research, Inc. / Foothill Family Clinic South
Salt Lake City, Utah, 84121, United States
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Johnson County Clin-Trials, Inc.
Lenexa, Kansas, 66219, United States
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Optimal Research, LLC
Peoria, Illinois, 61610, United States
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Tekton Research Inc
Austin, Texas, 78745, United States
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