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A Study to Evaluate the Safety and Immunogenicity of the mRNA COVID-19 Vaccines in Healthy Children Between 6 Months to Less Than 6 Years of Age

Launched by MODERNATX, INC. · Jun 27, 2022

Trial Information

Current as of September 12, 2025

Recruiting

Keywords

Coronavirus Disease 2019 Covid 19

ClinConnect Summary

This clinical trial is studying the safety and effectiveness of two mRNA COVID-19 vaccines in healthy children aged 6 months to less than 6 years. The trial will look at how well these vaccines work to help the immune system recognize and fight the virus that causes COVID-19, especially against certain variants. There are different parts to the study: some children will receive the vaccine for the first time, while others who have already had two doses of another vaccine will get a booster dose.

To participate, children need to be within the specified age range and generally healthy, meaning any ongoing medical conditions should be stable. For example, children with asthma or diabetes can join as long as their condition is well-managed. Parents or guardians will need to understand the study and provide consent for their child to participate. Throughout the trial, children will receive the vaccine and be monitored for any side effects or reactions. This study is a chance to help protect young children against COVID-19 and contribute to our understanding of how these vaccines work in this age group.

Gender

ALL

Eligibility criteria

  • Inclusion Criteria:
  • The participant is 6 months to \<6 years for Parts 1, 2, and 3; 2 years to \<5 years for Part 4A; and 6 months to \<2 years for Part 4B at the time of consent (Screening Visit). Note: for Part 1, participant must be at least 6 months old and must not have reached 6 years of age at the time of administration of first dose. For Part 4B, the participant must be at least 6 months old and must not have reached 2 years of age at the time of administration of first dose.
  • If the participant has a chronic disease (that is, asthma, diabetes mellitus, cystic fibrosis, human immunodeficiency virus \[HIV\] infection), the disease should be stable, per investigator assessment, so that the participant can be considered eligible for inclusion. Stable diseases are those which have had no change in their status or in the medications required to control them in the 6 months prior to Screening Visit. Note: a change in medication for dose optimization (that is, insulin dose changes, adjustments for age-related weight gain), change within class of medication, or reduction in dose are not considered signs of instability.
  • In the investigator's opinion, the parent(s)/legally authorized representative(s) (LAR\[s\]) understand and are willing and physically able to comply with protocol-mandated follow-up, including all procedures and provide written informed consent.
  • The participant is 2 years or older and has a body mass index (BMI) at or above the second percentile according to World Health Organization (WHO) Child Growth Standards at the Screening Visit.
  • OR
  • The participant is less than 2 years of age and the participant's height and weight are both at or above the second percentile according to WHO Child Growth Standards at the Screening Visit.
  • Special inclusion criteria for participants aged 6 months to \< 12 months:
  • The participant was born at full-term (≥ 37 weeks gestation) with a minimum birth weight of 2.5 kilograms (kg).
  • Inclusion criteria for Part 2:
  • The participant must have received 2 doses of mRNA-1273, approximately 28 to 35 days apart, as 25-μg primary series, and second dose was given at least 4 months prior to enrollment.
  • Inclusion criteria for Part 3 only:
  • - The participant must have received an age-appropriate immunization series of an authorized/approved COVID-19 vaccine, with the last dose given at least 4 months prior to enrolment (Previous vaccines NOT allowed are: XBB.1.5-containing formulation).
  • Exclusion Criteria:
  • Has a known history of SARS-CoV-2 infection (that is, reported AE of COVID-19 or asymptomatic SARS-CoV-2 infection during Study mRNA-1273-P204 at the time of rollover into mRNA-1273-P306 or during Part 1 at the time of rollover into Part 3) in the 90 days prior to dosing in this study.
  • Is acutely ill or febrile 24 hours prior to or at the Screening Visit. Fever is defined as a body temperature ≥ 38.0°Celsius (C)/≥ 100.4°Fahrenheit (F). Participants who meet this criterion may have visits rescheduled within the relevant study visit windows. Afebrile participants with minor illnesses can be enrolled at the discretion of the investigator.
  • For Parts 1 and 4, participant has previously been administered an investigational or approved CoV (that is, SARS-CoV-2, SARS-CoV, Middle East respiratory syndrome coronavirus \[MERS-CoV\]) vaccine. For Part 2, participant who received any approved/investigational CoV vaccine are ineligible to participate except for those who received mRNA-1273 (prototype) vaccine.
  • Has undergone treatment with investigational or approved agents for prophylaxis against COVID-19 (including receipt of SARS-CoV-2 monoclonal antibodies for prophylaxis or treatment) within 90 days prior to enrollment.
  • Has a known hypersensitivity to a component of the vaccine or its excipients. Hypersensitivity includes, but is not limited to, anaphylaxis or immediate allergic reaction of any severity to a previous dose of an mRNA COVID-19 vaccine or any of its components (including polyethylene glycol \[PEG\] or immediate allergic reaction of any severity to polysorbate).
  • Has a medical or psychiatric condition that, according to the investigator's judgment, may pose additional risk as a result of participation, interfere with safety assessments, or interfere with interpretation of results.
  • * Has a history of diagnosis or condition that, in the judgment of the investigator, may affect study endpoint assessment or compromise participant safety, specifically the following:
  • Congenital or acquired immunodeficiency, other than well-controlled HIV infection.
  • Chronic hepatitis or suspected active hepatitis
  • A bleeding disorder that is considered a contraindication to IM injection or phlebotomy
  • Dermatologic conditions that could affect local solicited AR assessments
  • Any prior diagnosis of malignancy (excluding nonmelanoma skin cancer)
  • * Has received the following:
  • Any routine vaccination with inactivated or live vaccine(s) within 14 days prior to study vaccination or plans to receive such a vaccine through 14 days following study vaccination.
  • Note: This excludes influenza vaccine that may be given anytime, but ideally at least 7 days before study dose. If a participant receives an influenza vaccine, this should be captured within the concomitant medication electronic case report form (eCRF).
  • Systemic immunosuppressants or immune-modifying drugs for \>14 days in total within 6 months prior to the day of enrollment (for corticosteroids, ≥1 milligrams (mg)/kg/day or ≥ 10 mg/day prednisone equivalent, if participant weighs \>10 kg). Participants may have visits rescheduled for enrollment if they no longer meet this criterion within the Screening Visit window. Inhaled, nasal, and topical steroids, and palivizumab are allowed.
  • Intravenous (IV) or subcutaneous (SC) blood products (red cells, platelets, immunoglobulins) within 3 months prior to enrollment.
  • Note: Other inclusion and exclusion criteria may apply.

About Modernatx, Inc.

ModernaTX, Inc. is a pioneering biotechnology company focused on developing transformative medicines based on messenger RNA (mRNA) technology. Established with a commitment to addressing unmet medical needs, Moderna leverages its proprietary platform to create innovative therapies and vaccines for a variety of diseases, including infectious diseases and cancer. The company gained global recognition for its rapid development of an mRNA-based COVID-19 vaccine, showcasing its agility and expertise in the biopharmaceutical landscape. Through robust clinical trials and a commitment to scientific excellence, ModernaTX aims to redefine the future of medicine and enhance patient outcomes worldwide.

Locations

Tampa, Florida, United States

Lexington, Kentucky, United States

Minneapolis, Minnesota, United States

Aurora, Colorado, United States

Oklahoma City, Oklahoma, United States

Charleston, South Carolina, United States

Columbia, Missouri, United States

Omaha, Nebraska, United States

Charleston, South Carolina, United States

Houston, Texas, United States

Metairie, Louisiana, United States

Jacksonville, Florida, United States

Memphis, Tennessee, United States

Edinburg, Texas, United States

Decatur, Georgia, United States

Chicago, Illinois, United States

Hastings, Nebraska, United States

Doral, Florida, United States

Houston, Texas, United States

Burke, Virginia, United States

Washington, District Of Columbia, United States

Macon, Georgia, United States

Richmond, Virginia, United States

Binghamton, New York, United States

East Syracuse, New York, United States

Minneapolis, Minnesota, United States

Charleston, South Carolina, United States

Victoria, Texas, United States

Lincoln, Nebraska, United States

Montebello, California, United States

Frisco, Texas, United States

Meridian, Idaho, United States

Houston, Texas, United States

Bessemer, Alabama, United States

Banning, California, United States

Overland Park, Kansas, United States

East Greenwich, Rhode Island, United States

Cedar Park, Texas, United States

San Juan, Puerto Rico

Paramount, California, United States

Lexington, Kentucky, United States

Lafayette, Louisiana, United States

Lincoln, Nebraska, United States

Kissimmee, Florida, United States

Albuquerque, New Mexico, United States

Miami, Florida, United States

E. Amherst, New York, United States

Metairie, Louisiana, United States

Albuquerque, New Mexico, United States

Austin, Texas, United States

Beaumont, Texas, United States

Panama, Panama

Panama, Panama

Panama, Panama

Panama, Panama

Panama, Panama

Santo Domingo Este, Santo Domingo, Dominican Republic

Santo Domingo Iesta, Santo Domingo, Dominican Republic

Santo Domingo, Dominican Republic

Panama, Panama

Panama, Panama

Santiago, Region Metropolitana, Chile

Higüey, La Altagracia, Dominican Republic

Medellin, Antioquia, Colombia

Barranquilla, Atlántico, Colombia

Cartagena, Bolivar, Colombia

Aguazul, Casanare, Colombia

Yopal, Casanare, Colombia

Bogotá, Cundinamarca, Colombia

Bogotá, Distrito Capital De Bogotá, Colombia

Acacias, Meta, Colombia

Santo Domingo De Guzmán, Distrito Nacionalsanto Domingo, Dominican Republic

Caba, Ciudad Autónoma De Buenos Aires, Argentina

Ciudad Autónoma De Buenos Aires, Ciudad Autónoma De Buenosaires, Argentina

San Miguel De Tucumán, Tucumán, Argentina

Ciudad Autónoma De Buenos Aires, Argentina

Caba, Argentina

Ciudad Autónoma De Buenos Aires, Argentina

San Miguel De Tucumán, Argentina

Barranquilla, Colombia

Bogotá, Colombia

Patients applied

0 patients applied

Timeline

First submit

Trial launched

Trial updated

Estimated completion

Not reported

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