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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

An Open-Label, Phase 3 Study to Evaluate the Safety and Immunogenicity of mRNA Vaccines for SARS-CoV-2 Variants in Participants Aged 6 Months to < 6 Years

Status
Completed
Phases
Phase 3
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT05436834
Enrollment
1807
Registered
2022-06-29
Start date
2022-06-21
Completion date
2025-10-20
Last updated
2025-11-26

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

SARS-CoV-2

Keywords

Coronavirus disease 2019, COVID-19

Brief summary

This study will evaluate the safety and immunogenicity of the mRNA-1273.214 vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant of concerns (VOCs) in participants aged 6 months to \<6 years, when administered as a primary series in SARS-CoV-2 vaccine-naïve participants (Part 1) and a single booster dose (BD) given to participants who previously received 2 doses of the mRNA-1273 vaccine as a primary series (Part 2); and will evaluate the safety and immunogenicity of the mRNA-1273.815 vaccine, when administered as a BD in participants aged 6 months to \<6 years (Part 3) and when administered to SARS-CoV-2 vaccine-naïve participants aged 2 years to \<5 years of age (Part 4).

Detailed description

Part 1 will enroll participants aged 6 months to \<6 years who have not been previously vaccinated against SARS-CoV-2. Participants will receive 2 doses of the mRNA-1273.214 vaccine. Part 2 will enroll participants aged 6 months to \<6 years who have previously been vaccinated with a mRNA-1273 primary series in Study mRNA-1273-P204 (NCT04796896). Participants will receive a single BD of the mRNA-1273.214 vaccine, at least 4 months after completion of the mRNA-1273 primary series. Part 3 will enroll participants aged 6 months to \<6 years who have previously been vaccinated with an authorized/approved COVID-19 vaccine. Participants will receive a BD of the mRNA-1273.815 vaccine at least 4 months after the last receipt of a COVID-19 vaccine. Part 4 will evaluate mRNA-1273.815 vaccine administered as a single dose to SARS-CoV-2 vaccine-naïve participants aged 2 years to \<5 years of age enrolled in Cohort A (Part 4A), compared to 2 doses given to SARS-CoV-2 vaccine-naïve participants aged 6 months to \<2 years enrolled in Cohort B (Part 4B).

Interventions

BIOLOGICALmRNA-1273.214

Sterile liquid for injection

BIOLOGICALmRNA-1273.815

Sterile liquid for injection

Sponsors

ModernaTX, Inc.
Lead SponsorINDUSTRY

Study design

Allocation
NON_RANDOMIZED
Intervention model
SEQUENTIAL
Primary purpose
PREVENTION
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
6 Months to 5 Years
Healthy volunteers
Yes

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

Design outcomes

Primary

MeasureTime frame
GM of the Serum Ab Level against Omicron BA.1 and Ancestral SARS-CoV-2 after mRNA-1273.214 Administration at Day 29Day 29
GM of the Serum Ab Level against Omicron XBB.1.5 after mRNA-1273.815 AdministrationUp to Day 57
Number of Participants with AEs Leading to WithdrawalUp to Day 394 (12 months after last dose)
Geometric Mean (GM) of the Serum Antibody (Ab) Level against Omicron BA.1 and Ancestral SARS-CoV-2 after mRNA-1273.214 Administration at Day 57Day 57
Seroresponse Rate (SRR) against Omicron BA.1 and Ancestral SARS-CoV-2 after mRNA-1273.214 AdministrationDay 29
Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs)Up to Day 8 (7 days post-vaccination)
Number of Participants with Unsolicited Adverse Events (AEs)Up to Day 29 (28 days after each injection)
Number of Participants with Medically-Attended AEs (MAAEs)Up to Day 394 (12 months after last dose)
Number of Participants with Serious AEs (SAEs)Up to Day 394 (12 months after last dose)
Number of Participants with Adverse Events of Special Interest (AESI)Up to Day 394 (12 months after last dose)

Secondary

MeasureTime frame
SRR against Omicron BA.1 and Ancestral SARS-CoV-2 after mRNA-1273.214 Administration Regardless of prior SARS-CoV-2 InfectionDay 57
GM of the Serum Ab Level against Omicron XBB.1.5 after mRNA-1273.815 Administration Regardless of prior SARS-CoV-2 InfectionUp to Day 57
SRR against Omicron XBB.1.5 after mRNA-1273.815 Administration Regardless of prior SARS-CoV-2 InfectionUp to Day 57

Countries

Argentina, Chile, Colombia, Dominican Republic, Panama, Puerto Rico, United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 8, 2026