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

NCT04917861 | Completed Phase 2 Results DMC FDA Drug

• 2 other identifiers: mRNA-1893-P201HHSO100201600029C
• Study Type: interventional
• Target: 808
• Locations: 2 countries
• Sites: 11

Brief 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.

Conditions

Zika Virus

Keywords

Flavivirus; mRNA-1893; Zika vaccine; Moderna

Outcome Measures

Primary Outcomes (8)

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

  Solicited ARs (local and systemic) were collected in the electronic diary. Local ARs included: pain, erythema (redness), swelling/induration (hardness). Systemic ARs included: headache, fatigue, myalgia (muscle aches all over the body), arthralgia (aching in several joints), nausea/vomiting, body temperature (potentially fever), and chills. A summary of all serious adverse events (SAEs) and all nonserious adverse events (AEs) ("Other"), regardless of causality, is in Reported "Adverse Events" section.

  Up to 7 days post-vaccination

• Number of Participants With Unsolicited Adverse Events (AEs)

  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. Unsolicited AEs were AEs that were not included in the protocol-defined solicited ARs. A treatment-emergent adverse event (TEAE) was defined as any AE not present before exposure to vaccine or any AE already present that worsened in intensity or frequency after exposure. A summary of all SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

  Up to 28 days post-vaccination

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

  An SAE was defined as any AE that resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, was a congenital anomaly/birth defect, or was an important medical event. An AESI was an AE (serious or nonserious) of scientific and medical concern specific to the Sponsor's product or program, for which ongoing monitoring and immediate notification by the Investigator to the Sponsor were required. A summary of all SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

  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)

  An MAAE was an AE that led to an unscheduled visit to a healthcare practitioner. Note that the generation of the tables for the MAAE data for the Main Study occurred after the start of the Extension Period. Therefore, some of the MAAE data for this outcome measure may appear both in the Main Study and the Extension Period. A summary of all SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

  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)

  Antibody values reported as below the lower limit of quantification (LLOQ) were replaced by 0.5 \* LLOQ. Values that were greater than the upper limit of quantification (ULOQ) were converted to the ULOQ. LLOQ=91; ULOQ=24814. 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.

  Day 57

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

  Antibody values reported as below the LLOQ were replaced by 0.5 \* LLOQ. Values that were greater than the ULOQ were converted to the ULOQ. LLOQ=91; ULOQ=24814. 95% CI was calculated based on the t-distribution of the log-transformed values, then back transformed to the original scale for presentation.

  Day 57

• Percentage of Participants With Seroconversion at Day 57, as Measured by PRNT50

  Seroconversion was defined as an increase in ZIKV-specific nAb titer from below the LLOQ to a titer equal to or above LLOQ, or an increase of at least 4-fold in ZIKV-specific nAb titer in participants with pre-existing nAb titers. LLOQ=91; ULOQ=24814.

  Day 57

• Percentage of Participants With Seroconversion at Day 57, as Measured by PRNT80

  Seroconversion was defined as an increase in ZIKV-specific nAb titer from below the LLOQ to a titer equal to or above LLOQ, or an increase of at least 4-fold in ZIKV-specific nAb titer in participants with pre-existing nAb titers. LLOQ=91; ULOQ=24814.

  Day 57

Secondary Outcomes (12)

• GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80

  Days 1, 8, 29, and 36

• GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN)

  Days 1, 8, 29, 36, and 57

• Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80

  Days 8, 29, 36, and 57

• GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN

  Days 8, 29, 36, and 57

• Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80

  Days 8, 29, and 36

Other Outcomes (1)

• Number of Deaths Related to Study Drug

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

Study Arms (4)

mRNA-1893 Low Dose (2-Dose Regimen)

EXPERIMENTAL

Participants will receive mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day (-3/+7 days) interval between vaccinations (administered on Day 1 and Day 29).

Biological: mRNA-1893

mRNA-1893 High Dose (2-Dose Regimen)

EXPERIMENTAL

Participants will receive mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day (-3/+7 days) interval between vaccinations (administered on Day 1 and Day 29).

Biological: mRNA-1893

mRNA-1893 High Dose (1-Dose Regimen)

EXPERIMENTAL

Participants will receive placebo matching to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There will be 28-day (-3/+7 days) interval between vaccinations.

Biological: mRNA-1893; Biological: Placebo

Placebo

PLACEBO COMPARATOR

Participants will receive placebo matching to mRNA-1893 administered as a 2-dose regimen with 28-day (-3/+7 days) interval between vaccinations (administered on Day 1 and Day 29).

Biological: Placebo

Interventions

mRNA-1893 BIOLOGICAL

Solution for injection

Also known as: Zika vaccine

mRNA-1893 High Dose (1-Dose Regimen); mRNA-1893 High Dose (2-Dose Regimen); mRNA-1893 Low Dose (2-Dose Regimen)

Placebo BIOLOGICAL

0.9% sodium chloride solution for injection

Placebo; mRNA-1893 High Dose (1-Dose Regimen)

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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.

You may not qualify if:

• 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 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.

Sponsors & Collaborators

• ModernaTX, Inc.: lead

Study Sites (11)

Meridian Clinical Research (Sioux City, IA)

Sioux City, Iowa, 51106, United States

Location

Johnson County Clin-Trials

Lenexa, Kansas, 66219, United States

Location

Benchmark Research - Fort Worth

Fort Worth, Texas, 76135, United States

Location

Clinical Research Puerto Rico, Inc.

Guayama, PR, 00784, Puerto Rico

Location

Ponce Medical School Foundation, Inc.

Ponce, PR, 00713, Puerto Rico

Location

Ponce Medical School Foundation, Inc.

Ponce, PR, 00716, Puerto Rico

Location

Clinical Research Puerto Rico, Inc.

San Juan, PR, 00909, Puerto Rico

Location

Latin Clinical Trial Center, Inc.

San Juan, PR, 00909, Puerto Rico

Location

GCM Medical Group, PSC

San Juan, PR, 00917, Puerto Rico

Location

Carribean Medical Research

San Juan, PR, 00918, Puerto Rico

Location

University of Puerto Rico

San Juan, PR, 00935, Puerto Rico

Location

MeSH Terms

Conditions

Zika Virus Infection

Interventions

GLS-5700 vaccine

Condition Hierarchy (Ancestors)

Mosquito-Borne Diseases; Vector Borne Diseases; Infections; Arbovirus Infections; Virus Diseases; Flavivirus Infections; Flaviviridae Infections; RNA Virus Infections

Results Point of Contact

• Title: Moderna WeCare Team
• Organization: ModernaTX, Inc.

WeCareClinicalTrials@modernatx.com

+1-866-663-3762

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: Yes

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 2, 2021
• First Posted: June 8, 2021
• Study Start: June 7, 2021
• Primary Completion: July 26, 2024
• Study Completion: July 26, 2024
• Last Updated: September 25, 2025
• Results First Posted: September 25, 2025

Record last verified: 2025-08

Locations

US (3); PR (8)