A Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of mRNA-1283 in Participants ≥6 Months to <12 Years of Age

September 2, 2026 updated by: ModernaTX, Inc.

A Phase 2, Randomized, Observer-Blind, Dose Ranging Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of mRNA-1283 in Participants ≥6 Months to <12 Years of Age

This study will evaluate 2 dose levels of mRNA-1283 in participants ≥6 months to <12 years to determine the optimal dose level per age group.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

mRNA-1283 will be administered at 2 different dose levels (Dose Level 1 and Dose Level 2), with mRNA-1273 serving as the active comparator. Dose Level 1 will be the lower dose, and Dose Level 2 will be the higher dose.

The study will consist of 2 cohorts. In Cohort 1, mRNA-1283 will be administered as a single dose to participants aged ≥2 to <12 years, regardless of prior coronavirus disease 2019 (COVID-19) vaccination status, with mRNA-1273 included as a comparator. In Cohort 2, mRNA-1283 will be administered as a 2-dose series to participants aged ≥6 months to <2 years who are previously unvaccinated for COVID-19, with mRNA-1273 included as a comparator.

Study Type

Interventional

Enrollment (Estimated)

300

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Argentina
    • Buenos Aires
      • Ciudad Autonoma, Buenos Aires, Argentina
        • Fundacion Respirar - Consultorios Medicos Dra De Salvo
    • Santa Fe Province
      • Casilda, Santa Fe Province, Argentina
        • Instituto Medico de la Fundacion Estudios Clinicos
    • Tucumán Province
      • San Miguel de Tucumán, Tucumán Province, Argentina
        • Hospital del Nino Jesus
  • Dominican Republic
    • Distrito Nacional (Santo Domingo)
      • Cristo Rey, Distrito Nacional (Santo Domingo), Dominican Republic, 10501
        • Medvacplus Srl Fundacion Clinica Cruz Jiminian
      • Santo Domingo, Distrito Nacional (Santo Domingo), Dominican Republic, 10306
        • Instituto Dermatologico y Cirugia de Piel ''Dr. Huberto Bogaert Diaz'' (IDCP-DHBD)
    • La Altagracia Province
      • Salvaleón de Higüey, La Altagracia Province, Dominican Republic
        • Hospital General y de Especialidades Nuestra Señora de la Altagracia
    • Nacional
      • Santo Domingo, Nacional, Dominican Republic, 11901
        • Hospital Materno Infantil San Lorenzo De Los Mina
  • Mexico
    • Jalisco
      • Guadalajara, Jalisco, Mexico
        • Centro de Investigacion Clínica y Medicina Traslacional (CIMeT)
    • Mexico City
      • Mexico City, Mexico City, Mexico
        • Hospital Infantil de México Federico Gómez - Pediatric Gastroenterology
      • Mexico City, Mexico City, Mexico
        • Instituto Nacional de Pediatría
    • Querétaro
      • Querétaro City, Querétaro, Mexico
        • PanAmerican Clinical Research - Queretaro
    • Yucatán
      • Tizimín, Yucatán, Mexico
        • Centro de Salud Tizimin
  • Panama
    • Provincia de Panamá
      • Calidonia, Provincia de Panamá, Panama, 7094
        • CEVAXIN Avenida Mexico
      • La Chorrera, Provincia de Panamá, Panama
        • CEVAXIN Chorrera
      • Panama City, Provincia de Panamá, Panama
        • CEVAXIN 24 de Diciembre
      • Panama City, Provincia de Panamá, Panama
        • Instituto de Investigaciones Cienti-ficas Y Servicios de Alta Tecnologia Asociacion de Interes Panama; . Centro de Investigación, Innovación y Gestión del Conocimiento de Ciudad de la Salud, Caja de Seguro social
  • Puerto Rico
    • Puerto Rico
      • Ponce, Puerto Rico, Puerto Rico
        • Ponce Health Sciences University
      • San Juan, Puerto Rico, Puerto Rico, 00907
        • BRCR Global
  • United States
    • California
      • Ontario, California, United States, 91762
        • Orange County Research Center
    • Florida
      • Miami, Florida, United States, 33166
        • Hope Research Network
      • Miami, Florida, United States, 33167
        • Spotlight Research Center - Internal Medicine
      • Miami Lakes, Florida, United States, 33016
        • Indago Research and Health Cen
      • Tamarac, Florida, United States, 33321
        • MplusM - D&H Tamarac Research Center
    • Illinois
      • Chicago, Illinois, United States, 60621
        • Eagle Clinical Research, LLC
    • Michigan
      • Southfield, Michigan, United States, 48075
        • Great Lakes Research Institute -Southfield
    • Ohio
      • South Euclid, Ohio, United States, 44121
        • Senders Pediatrics
    • Texas
      • Beaumont, Texas, United States, 77701
        • REX Clinical Trials
      • Brownsville, Texas, United States, 78520
        • PanAmerican Clinical Research, LLC.
    • Utah
      • South Ogden, Utah, United States, 84403
        • South Ogden Family Medicine
    • Virginia
      • Richmond, Virginia, United States, 23226
        • Clinical Research Partners
    • Washington
      • Seattle, Washington, United States, 98105
        • Childrens Hospital Regional Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

Yes

Description

Key Inclusion Criteria:

  • Participant is male or female, between ≥2 years to <12 years of age for Cohort 1 or ≥6 months to <2 years of age for Cohort 2 (calculated from date of birth) at the time of signing the informed consent/assent.
  • Participant is in good general health as determined by medical evaluation including medical history and physical examination. Participants with chronic but stable conditions (eg, gastroesophageal reflux disease, asthma) may be eligible to enroll, provided the condition is well-controlled and not expected to interfere with study participation or outcomes.
  • For participants in Cohort 2: the participant was born at ≥37 weeks, with a minimum birth weight of 2.5 kilograms, without fetal growth restriction.
  • Female participants of nonchildbearing potential may be enrolled in the study. Nonchildbearing potential is defined as premenarche. The investigator is responsible for review of medical history, menstrual history, and recent sexual activity to decrease the risk for inclusion of a participant with an early undetected pregnancy. If childbearing potential is unclear (for example, amenorrhea in athletes) and a menstrual cycle cannot be confirmed before first dose of study intervention, additional evaluation should be considered.
  • Female participants who have reached menarche may be enrolled in the study if all of the following criteria are fulfilled:
  • Has a negative highly sensitive pregnancy test (urine or serum) as required by local regulations within 24 hours before the study intervention.
  • Is not currently chest/breastfeeding.
  • Has been using a highly effective contraceptive method or has abstained from all activities that could lead to pregnancy for at least 28 days prior to the study injection (Day 1). The investigator should evaluate the potential for contraceptive method failure (for example, noncompliance, recently initiated) in relationship to the study injection.
  • Has agreed to continue adequate contraception through the end of study. Contraceptive use by participants should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.

Key Exclusion Criteria:

  • History of SARS-CoV-2 infection within 3 months prior to enrollment.
  • Acutely ill or febrile (temperature ≥38.0℃elsius [100.4°Fahrenheit]) within 72 hours prior to or at the screening visit or Day 1. Participants who are acutely ill or febrile may be scheduled for a separate dosing visit within the protocol-specified window for screening and will retain their initially assigned participant number. Afebrile participants with minor illnesses can be enrolled at the discretion of the Investigator.
  • Any medical, psychiatric, or occupational condition, including reported history of drug, or alcohol abuse in the parent(s)/ legally authorized representative(s), that, in the opinion of the investigator, might pose additional risk due to child's participation in the study, could interfere with safety assessments, or could interfere with the interpretation of study results.
  • Receipt of the 2026-2027 formulation of a COVID-19 vaccine at any time prior to enrollment.
  • Receipt of any COVID-19 vaccine within 6 months prior to enrollment.
  • Receipt of any nonstudy vaccination within 14 days (28 days for live vaccines) prior to study intervention or plans to receive a nonstudy vaccine through 14 days after administration of study intervention.
  • Received systemic immunosuppressive treatment, including long-acting biological therapies that affect immune responses (for example, infliximab), within 180 days prior to Day 1 (baseline) or plans to do so during the study.
  • Received systemic immunoglobulins or blood products within 90 days prior to the screening visit or plans to receive them during the study. Exception: Nirsevimab and clesrovimab are allowed.
  • For infants who receive breast milk, maternal receipt of systemic immunosuppressive therapy during lactation. This includes ≥10 milligrams/day of prednisone or equivalent for 14 days or more, or other immunomodulating agents (for example, biologics, calcineurin inhibitors, disease-modifying agents) that may be transferred via breastmilk and impact infant immune development or vaccine response.
  • Has participated in an interventional clinical study within 28 days prior to the screening visit based on the medical history interview or plans to do so while participating in this study.
  • Has been placed under the control or protection of an agency, organization, institution, or entity by the courts, the government, or a government body, acting in accordance with powers conferred on them by laws, and regulation. Does not include a child who is adopted or has an appointed legal guardian.
  • Receipt of any nonstudy vaccination within 14 days (28 days for live vaccines) prior to study intervention or plans to receive a nonstudy vaccine through 14 days after administration of study intervention.
  • History of any myocarditis, pericarditis, or myopericarditis

Note: Other inclusion and exclusion criteria may apply.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Cohort 1: mRNA-1283 Dose Level 1
Participants aged 2 to <12 years receive one IM dose of on Day 1.
Biological: mRNA-1283
Sterile liquid for injection
Experimental: Cohort 1: mRNA-1283 Dose Level 2
Participants aged 2 to <12 years receive one IM dose of on Day 1.
Biological: mRNA-1283
Sterile liquid for injection
Active Comparator: Cohort 1: mRNA-1273
Participants aged 2 to <12 years receive one IM dose of on Day 1.
Biological: mRNA-1273
Sterile liquid for injection
Experimental: Cohort 2: mRNA-1283 Dose Level 1
Participants aged 6 months to <2 years receive two IM doses 28 days apart (Days 1 and 29).
Biological: mRNA-1283
Sterile liquid for injection
Experimental: Cohort 2: mRNA-1283 Dose Level 2
Participants aged 6 months to <2 years receive two IM doses of 28 days apart (Days 1 and 29).
Biological: mRNA-1283
Sterile liquid for injection
Active Comparator: Cohort 2: mRNA-1273
Participants aged 6 months to <2 years receive two IM doses 28 days apart (Day 1 and 29).
Biological: mRNA-1273
Sterile liquid for injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Cohort 1 and Cohort 2: Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs)
Time Frame: Day 1 through Day 7; 7 Days following injection
Day 1 through Day 7; 7 Days following injection
Cohort 1 and Cohort 2: Number of Participants with Unsolicited Adverse Events (AEs)
Time Frame: Day 1 through Day 28 (Cohort 1); 28 Days following injection (Cohort 2)
Day 1 through Day 28 (Cohort 1); 28 Days following injection (Cohort 2)
Cohort 1 and Cohort 2: Number of Participants with Any Medically Attended AEs (MAAEs), Serious AEs (SAEs), AEs of Special Interest (AESIs), and AEs Leading to Discontinuation from the Study
Time Frame: Day 1 through End of Study (Month 13)
Day 1 through End of Study (Month 13)
Cohort 1 and Cohort 2: Geometric Mean Value of Antibody Level Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Target Variant
Time Frame: Day 29 VISIT (Cohort 1), Day 57 VISIT (Cohort 2)
Day 29 VISIT (Cohort 1), Day 57 VISIT (Cohort 2)
Cohort 1 and Cohort 2: Geometric Mean Fold Rise of Antibody Level Against SARS-CoV-2
Time Frame: Day 29 (Cohort 1), Day 57 (Cohort 2)
Day 29 (Cohort 1), Day 57 (Cohort 2)
Cohort 1 and Cohort 2: Number of Participants with Seroresponse Rate
Time Frame: Day 29 (Cohort 1), Day 57 (Cohort 2)
Day 29 (Cohort 1), Day 57 (Cohort 2)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

ModernaTX, Inc.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

September 1, 2026

Primary Completion (Estimated)

August 30, 2029

Study Completion (Estimated)

August 30, 2029

Study Registration Dates

First Submitted

September 2, 2026

First Submitted That Met QC Criteria

September 2, 2026

First Posted (Actual)

September 9, 2026

Study Record Updates

Last Update Posted (Actual)

September 9, 2026

Last Update Submitted That Met QC Criteria

September 2, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • mRNA-1283-P202

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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