CompletedPhase 2

A Study of Zika Vaccine mRNA-1893 in Adult Participants Living in Endemic and Non-Endemic Flavivirus Areas

United States, Puerto Rico808 participantsStarted 2021-06-07

Plain-language summary

This clinical study will evaluate the safety, tolerability, and reactogenicity of 2 dose levels of messenger RNA (mRNA)-1893 Zika vaccine in comparison to a placebo control in healthy participants who are flavivirus-seronegative and in participants who are flavivirus-seropositive.

Who can participate

Age range

18 Years – 65 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

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, as…

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

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

Timeframe: Up to 7 days post-vaccination

Number of Participants With Unsolicited Adverse Events (AEs)

Timeframe: Up to 28 days post-vaccination

Number of Participants With Serious Adverse Events (SAEs), AEs of Special Interest (AESIs)

Timeframe: Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period

Number of Participants With Medically Attended AEs (MAAEs)

Timeframe: Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period

Geometric Mean Titer (GMT) of Zika Virus (ZIKV)-Specific Neutralizing Antibodies (nAbs) at Day 57, as Measured by 50% Plaque Reduction Neutralization Test (PRNT50)

Timeframe: Day 57

GMT of ZIKV-specific nAbs at Day 57, as Measured by 80% Plaque Reduction Neutralization Test (PRNT80)

Timeframe: Day 57

Trial details

NCT IDNCT04917861

SponsorModernaTX, Inc.

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2024-07-26

Results submitted2025-07-25

View on ClinicalTrials.gov More Zika Virus trials

Who can participate

Age range

18 Years – 65 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

What they're measuring

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

Timeframe: Up to 7 days post-vaccination

Number of Participants With Unsolicited Adverse Events (AEs)

Timeframe: Up to 28 days post-vaccination

Number of Participants With Serious Adverse Events (SAEs), AEs of Special Interest (AESIs)

Timeframe: Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period

Number of Participants With Medically Attended AEs (MAAEs)

Timeframe: Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period

Geometric Mean Titer (GMT) of Zika Virus (ZIKV)-Specific Neutralizing Antibodies (nAbs) at Day 57, as Measured by 50% Plaque Reduction Neutralization Test (PRNT50)

Timeframe: Day 57

GMT of ZIKV-specific nAbs at Day 57, as Measured by 80% Plaque Reduction Neutralization Test (PRNT80)

Timeframe: Day 57