Moderna's zika vaccine shows promise in Mid-Stage trial
NCT ID NCT04917861
First seen Jun 26, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This study tested Moderna's experimental Zika vaccine, mRNA-1893, in 808 healthy adults aged 18 to 65. Participants received one of two doses or a placebo, and researchers monitored side effects and immune responses. The goal was to confirm the vaccine's safety and ability to produce antibodies against the Zika virus.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- mRNA-1893 Zika vaccine
- What this could lead to
- If successful, this could lead to a safe and effective vaccine to prevent Zika virus infection, protecting people in affected regions.
- What could go wrong
- This is a Phase 2 trial focused on safety and immune response, not yet proving the vaccine prevents disease. Results may not guarantee effectiveness in real-world settings.
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
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Phase 2
Tests whether the treatment actually works, and watches for side effects, in a larger group.
- Participants
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808 people
The number who actually took part.
- Started
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Jun 2021
- Finished
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Jul 2024
- 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
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18 to 65 years
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
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.
Key Inclusion Criteria: * Understands and agrees to comply with the study procedures and provides written informed consent. * According to investigator assessment, is in good general health and can comply with study procedures. * Female participants of childbearing potential may be enrolled in the study if the participant: has a negative pregnancy test at the Eligibility Visit and on the day of the first investigational product (IP) injection; has practiced adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the first IP injection; has agreed to continue adequate contraception through 3 months following the last IP injection; and is not currently breastfeeding. Key Exclusion Criteria: * Participant is acutely ill or febrile (temperature ≥38.0°Celsius/100.4°Farenheight) on the day of the first or second vaccination. * Participant had prior administration of a ZIKV vaccine candidate during a clinical study investigation. * Participant had prior administration of a marketed dengue vaccine or dengue vaccine candidate under clinical study investigation. * Participant has a body mass index (BMI) from ≤18 or ≥35 kilograms (kg)/square meter (m\^2). * Participant has a history of myocarditis, pericarditis, or myopericarditis. * Participant has a history of a diagnosis or condition that, in the judgement of the investigator, is clinically unstable or may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures. "Clinically unstable" is defined as a diagnosis or condition requiring significant changes in management or medication within the 2 months prior to screening and includes ongoing work-up of an undiagnosed illness that could lead to a new diagnosis or condition. * Participant has any medical, psychiatric, or occupational condition, including reported history of drug or alcohol abuse, that in the opinion of the investigator, might pose a risk due to participation in the study or could interfere with the interpretation of study results. * Participant has as a history of anaphylaxis, urticaria, or other significant AR requiring medical intervention after receipt of a vaccine, including an mRNA vaccine or any components of an mRNA vaccine. * Participant has received or plans to receive a nonstudy vaccine (including authorized or approved vaccines for the prevention of COVID-19) ≤28 days prior to the first IP injection or within 28 days prior to or after any IP injection. Licensed influenza vaccine received within 14 days prior to the first IP injection or plans to receive a licensed influenza vaccine 14 days prior to through 14 days following each IP injection are not exclusionary. * Participant has received systemic immunoglobulins or blood products within 3 months prior to the day of enrollment. * Participant has donated ≥450 milliliters (mL) of blood products within 28 days of the Day 1 Visit. * Participant has participated in an interventional clinical study within 28 days prior to the day of enrollment or plans to do so while enrolled in this study.
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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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Benchmark Research - Fort Worth
Fort Worth, Texas, 76135, United States
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Carribean Medical Research
San Juan, PR, 00918, Puerto Rico
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Clinical Research Puerto Rico, Inc.
Guayama, PR, 00784, Puerto Rico
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Clinical Research Puerto Rico, Inc.
San Juan, PR, 00909, Puerto Rico
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GCM Medical Group, PSC
San Juan, PR, 00917, Puerto Rico
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Johnson County Clin-Trials
Lenexa, Kansas, 66219, United States
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Latin Clinical Trial Center, Inc.
San Juan, PR, 00909, Puerto Rico
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Meridian Clinical Research (Sioux City, IA)
Sioux City, Iowa, 51106, United States
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Ponce Medical School Foundation, Inc.
Ponce, PR, 00713, Puerto Rico
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Ponce Medical School Foundation, Inc.
Ponce, PR, 00716, Puerto Rico
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University of Puerto Rico
San Juan, PR, 00935, Puerto Rico
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