A Study to Evaluate Safety and Effectiveness of mRNA-1273 COVID-19 Vaccine in Healthy Children Between 6 Months of Age and Less Than 12 Years of Age

A Phase 2/3, Three-Part, Open-Label, Dose-Escalation, Age De-escalation and Randomized, Observer-Blind, Placebo-Controlled Expansion Study to Evaluate the Safety, Tolerability, Reactogenicity, and Effectiveness of mRNA-1273 SARS-CoV-2 Vaccine in Healthy Children 6 Months to Less Than 12 Years of Age

The primary goal for this study is to evaluate up to 3 dose levels of mRNA-1273 vaccine given to healthy children as intramuscular (IM) injection in 2 doses (in Parts 1 and 2) and 3 doses (in Part 3), and a third dose or an optional booster dose (BD) (in Parts 1 and 2).

Study Overview

• Status: Completed
• Conditions: SARS-CoV-2
• Intervention / Treatment: Biological: Placebo; Biological: mRNA-1273.214; Biological: mRNA-1273

Detailed Description

This is a Phase 2/3, 3-part, open-label, dose-escalation, age de-escalation, randomized, observer-blind, placebo-controlled, expansion study intended to infer the effectiveness of mRNA-1273 in children aged 6 months to less than 12 years.

Please access http://www.kidcovestudy.com for additional information, such as Study Overview, Participation, Site Locations along with contact numbers for each location for the study.

• Study Type: Interventional
• Enrollment (Actual): 11942
• Phase: Phase 2; Phase 3

Contacts and Locations

Study Locations

• Canada
  • Alberta
    • Calgary, Alberta, Canada, T3B 6A8
      • University of Calgary
  • British Columbia
    • Vancouver, British Columbia, Canada, V5Z 4H4
      • Children's and Women's Health Centre of British Columbia
  • Manitoba
    • Winnipeg, Manitoba, Canada, R3E 3P4
      • Winnipeg Children's Hospital, HSC-Winnipeg
  • Nova Scotia
    • Halifax, Nova Scotia, Canada, B3H 1
      • Dalhousie University
  • Ontario
    • Ottawa, Ontario, Canada, K1H 8L1
      • Childrens Hospital of Eastern Ontario
    • Toronto, Ontario, Canada, M5G 1X8
      • The Hospital for Sick Children (SickKids)
    • Toronto, Ontario, Canada, M9V 4B4
      • Dr. Anil K. Gupta Medicine Professional Corporation - Clinic/Outpatient Facility
  • Quebec
    • Pierrefonds, Quebec, Canada, H9H 4Y6
      • McGill University Health Centre-Vaccine Study Centre
• United States
  • Alabama
    • Birmingham, Alabama, United States, 35233-1711
      • Children's of Alabama
  • Arizona
    • Phoenix, Arizona, United States, 85015-1105
      • MedPharmics, LLC
  • California
    • Anaheim, California, United States, 92804-1866
      • Emmaus Research Center Inc
    • Banning, California, United States, 92220-3082
      • Velocity Clinical Research - Banning - ERN- PPDS
    • El Monte, California, United States, 91731
      • SeraCollection Research Services LLC
    • La Jolla, California, United States, 92037
      • UCSD Altman Clinical and Translational Research Institute Building
    • Los Angeles, California, United States, 90027
      • Kaiser Permanente Los Angeles Medical Center
    • Paramount, California, United States, 90723-5459
      • Center for Clinical Trials, LLC
    • San Diego, California, United States, 92123
      • Rady Childrens Hospital San Diego - PIN
    • Ventura, California, United States, 93003-5369
      • Carey Chronis MD Pediatric, Infant and Adolescent Medicine - FOMAT
  • Colorado
    • Aurora, Colorado, United States, 80045-7144
      • Children's Hospital Colorado - (CRS)
  • Connecticut
    • New Haven, Connecticut, United States, 06519-1712
      • Yale University School of Medicine
  • Florida
    • Doral, Florida, United States, 33166
      • Prohealth Research Center
    • Jacksonville, Florida, United States, 32209-6511
      • University of Florida Jacksonville
    • Kissimmee, Florida, United States, 34743
      • Kissimmee Clinical Research (KCR)
    • Miami, Florida, United States, 33155-4630
      • Allied Biomedical Research Institute
    • Pensacola, Florida, United States, 32503
      • Pensacola Research Consultants Inc. d/b/a Avanza Medical Research Center
    • Tampa, Florida, United States, 33613-3946
      • University of South Florida
  • Georgia
    • Atlanta, Georgia, United States, 30322-1014
      • Emory University School of Medicine
    • Decatur, Georgia, United States, 30030-3438
      • iResearch Atlanta, LLC
    • Savannah, Georgia, United States, 31405
      • iResearch Savannah
  • Idaho
    • Meridian, Idaho, United States, 83642-6246
      • Velocity Clinical Research - Boise - ERN - PPDS
  • Illinois
    • Chicago, Illinois, United States, 60611-2991
      • Ann and Robert H Lurie Childrens Hospital of Chicago
  • Kansas
    • El Dorado, Kansas, United States, 67042-2187
      • Alliance for Multispecialty Research -El Dorado
  • Kentucky
    • Lexington, Kentucky, United States, 40504-3516
      • University of Kentucky
    • Lexington, Kentucky, United States, 40517-8366
      • Michael W Simon, MD PSC
  • Louisiana
    • Baton Rouge, Louisiana, United States, 70809
      • Pennington Biomedical Research Center
    • Baton Rouge, Louisiana, United States, 70809
      • Our Lady of the Lake Regional Medical Center
    • Metairie, Louisiana, United States, 70006-4152
      • MedPharmics - Platinum
    • New Orleans, Louisiana, United States, 70112
      • Tulane Medical Center
  • Maryland
    • Baltimore, Maryland, United States, 21201-1519
      • University of Maryland School of Medicine
    • Chevy Chase, Maryland, United States, 20815
      • Javara inc.
    • Frederick, Maryland, United States, 21702-4747
      • The Pediatric Centre of Frederick
  • Massachusetts
    • Boston, Massachusetts, United States, 02114-2621
      • Massachusetts General Hospital
    • Boston, Massachusetts, United States, 02111-1552
      • Tufts University - Boston - PPDS
    • Fall River, Massachusetts, United States, 02721-1778
      • Pediatric Associates of Fall River
    • Worcester, Massachusetts, United States, 01655
      • University of Massachusetts Medical School
    • Worcester, Massachusetts, United States, 01655
      • UMass Memorial Medical Center
  • Michigan
    • Detroit, Michigan, United States, 48202-2608
      • Henry Ford Health System
  • Minnesota
    • Minneapolis, Minnesota, United States, 55454
      • University of Minnesota Masonic Children's Hospital
    • Minneapolis, Minnesota, United States, 55402-2700
      • Clinical Research Institute, Inc - CRN - PPDS
  • Mississippi
    • Petal, Mississippi, United States, 39465
      • MediSync Clinical Research Hattiesburg Clinic
  • Missouri
    • Columbia, Missouri, United States, 65212-1000
      • University of Missouri Health Care System
    • Saint Louis, Missouri, United States, 63110-1010
      • Washington University in St. Louis
  • Nebraska
    • Hastings, Nebraska, United States, 68901
      • Meridian Clinical Research (Hastings, Nebraska)
    • Norfolk, Nebraska, United States, 68701-2669
      • Meridian Clinical Research (Norfolk-Nebraska) - Platinum - PPDS
    • Omaha, Nebraska, United States, 68114-3723
      • Quality Clinical Research - PPDS
  • New Mexico
    • Albuquerque, New Mexico, United States, 87102
      • MedPharmics, LLC
    • Albuquerque, New Mexico, United States, 87106-2719
      • University of New Mexico
  • New York
    • Binghamton, New York, United States, 13901-1046
      • Meridian Clinical Research (Endwell-New York) - Platinum - PPDS
    • Cortland, New York, United States, 13045-9398
      • Certified Research Associates
    • East Syracuse, New York, United States, 13057
      • Child Healthcare Associates - East Syracuse
    • Rochester, New York, United States, 14642-0001
      • University of Rochester Medical Center
    • Stony Brook, New York, United States, 11794-0001
      • Stony Brook University Medical Center
  • North Carolina
    • Charlotte, North Carolina, United States, 28208
      • Onsite Clinical Solutions, LLC
    • Winston-Salem, North Carolina, United States, 27101-4263
      • Javara Inc. - Winston-Salem
  • Ohio
    • Cincinnati, Ohio, United States, 45229-3026
      • Cincinnati Children's Hospital Medical Center - PIN
  • Oklahoma
    • Oklahoma City, Oklahoma, United States, 73112-4703
      • Lynn Health Science Institute - ERN - PPDS
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19104-4319
      • Children's Hospital of Philadelphia
    • Pittsburgh, Pennsylvania, United States, 15213-1481
      • Children's Hospital of Pittsburgh
  • Rhode Island
    • Warwick, Rhode Island, United States, 02886-1617
      • Velocity Clinical Research - Providence - ERN - PPDS
  • South Carolina
    • Charleston, South Carolina, United States, 29414-5834
      • Coastal Pediatric Associates
    • Charleston, South Carolina, United States, 29425-8903
      • Medical University of South Carolina- PPDS
    • North Charleston, South Carolina, United States, 29406-9170
      • Palmetto Pediatrics
  • Tennessee
    • Nashville, Tennessee, United States, 37232-0011
      • Vanderbilt University Medical Center
    • Nashville, Tennessee, United States, 37208-3501
      • Meharry Medical College - Clinical and Translational Research Center & Meharry Medical College - Pediatric Department
  • Texas
    • Austin, Texas, United States, 78745
      • Tekton Research - Texas - Platinum - PPDS
    • Edinburg, Texas, United States, 78539-8462
      • BRCR Global Texas
    • El Paso, Texas, United States, 79902-1139
      • Pininos Pediatric Services
    • Houston, Texas, United States, 77081
      • Texas Center for Drug Development, Inc
    • Houston, Texas, United States, 77030-3411
      • Baylor College of Medicine
    • Houston, Texas, United States, 77008-1398
      • Ventavia Research Group - Platinum - PPDS
    • Houston, Texas, United States, 77055-1626
      • West Houston Clinical Research - Hunt
    • Houston, Texas, United States, 77375-6579
      • Cyfair Clinical Research Center - ERN- PPDS
    • Plano, Texas, United States, 75024
      • Village Health Partners - HUNT
    • Port Lavaca, Texas, United States, 77901-5531
      • Victoria Clinical Research
    • The Woodlands, Texas, United States, 77382
      • Javara, Inc.
    • Victoria, Texas, United States, 77901
      • Crossroads Clinical Research (Victoria)
  • Utah
    • Layton, Utah, United States, 84041
      • Tanner Clinic
    • West Jordan, Utah, United States, 84088
      • Advanced Clinical Research/Velocity Clinical Research
  • Virginia
    • Burke, Virginia, United States, 22015-1635
      • PI-Coor Clinical Research, LLC
    • Richmond, Virginia, United States, 23226
      • Clinical Research Partners, LLC
  • Wisconsin
    • Madison, Wisconsin, United States, 53792-0001
      • University Of Wisconsin - Madison

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 6 months to 11 years (Child)
• Accepts Healthy Volunteers: Yes

Description

Key Inclusion Criteria:

• For participants with chronic diseases (such as, asthma, diabetes mellitus, cystic fibrosis, human immunodeficiency virus [HIV] infection), the disease should be stable, per investigator assessment.
• Investigator assessment that the parent(s)/legally acceptable representatives understand and are willing and physically able to comply with protocol mandated follow-up, including all procedures, written informed consent is provided, and participants provide assent.
• For children 2 years of age or older has a body mass index at or above the third percentile according to World Health Organization (WHO) Child Growth Standards at the Screening Visit.
• For children 6 months to <12 months of age: born at full-term with a minimum birth weight of 2.5 kilograms (kg).
• For female participants of childbearing potential: negative pregnancy test, adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the first injection, agreement to continue adequate contraception or abstinence through 3 months following the second injection (Day 29) and the third dose in Part 3 (Day 149/booster dose Day 1), and not currently breastfeeding.

Key Exclusion Criteria:

• Known history of SARS-CoV-2 infection within 2 weeks prior to administration of vaccine or known close contact with anyone with laboratory-confirmed SARS-CoV-2 infection or COVID-19 within 2 weeks prior to administration of vaccine.
• Prior administration of an investigational or approved CoV (such as, SARS-CoV-2, SARS CoV, Middle East Respiratory Syndrome CoV) vaccine.
• Treatment with investigational or approved agents for prophylaxis against COVID 19 (such as, receipt of SARS-CoV-2 monoclonal antibodies) within 6 months prior to enrollment.
• Known hypersensitivity to a component of the vaccine or its excipients.
• 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.
• History of a diagnosis or condition that, in the judgment of the investigator, may affect study endpoint assessment or compromise participant safety.
• Received any non-study vaccine within 14 days before or after any dose of vaccine (except for seasonal influenza vaccine, which is not permitted within 14 days before or after any dose of vaccine)
• Received intravenous or subcutaneous blood products (red blood cells, platelets, immunoglobulins) within 3 months prior to Day 1
• Participated in an interventional clinical study within 28 days prior to Day 0 or plans to donate blood products while participating in this study.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: mRNA-1273; Part 1: Participants will receive 2 IM injections of mRNA-1273 at doses pre-specified for this study, on Days 1 and 29. Participants will be offered an optional BD of mRNA-1273 lower than the dose chosen for primary series, ≥6 months after Dose 2. After protocol amendment (PA) 9, participants who have not yet received a BD will be offered a BD with mRNA-1273.214. Part 2: Participants will receive 2 IM injections of mRNA-1273 at dose selected from Part 1 on Days 1 and 29. Participants (6 to <12 year) will be offered an optional BD of mRNA-1273 lower than the dose chosen for primary series, ≥6 months after Dose 2. After PA 9, participants who have not yet received a BD will be offered a BD with mRNA-1273.214. Part 3: Participants will receive 2 IM injections of mRNA-1273 on Days 1 and 29 as primary series then 1 IM injection as Dose 3, on Day 149 ≥3 months and ≤5 months after receipt of Dose 2 of primary series. All 3 injections will be administered at lower dose than that of Part 1.	Biological: mRNA-1273.214; Sterile liquid for injection; Biological: mRNA-1273; Sterile liquid for injection
Placebo Comparator: Placebo; Part 2 only: Participants will receive 2 IM injections of mRNA-1273-matching placebo on Day 1 and Day 29. Participants (6 to <12 year old) will be offered an optional BD of mRNA-1273 at a dose lower than the dose that was chosen for the primary series for this age group, at least 6 months post-cross-over Dose 2. After PA 9, participants who have not yet received a BD will be offered a BD with mRNA-1273.214.	Biological: Placebo; 0.9% sodium chloride (normal saline) injection; Biological: mRNA-1273.214; Sterile liquid for injection; Biological: mRNA-1273; Sterile liquid for injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Parts 1, 2, and 3: Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs)	Solicited ARs were collected in an electronic diary (eDiary). Local ARs: injection site pain, erythema (redness), swelling/induration (hardness); and axillary (underarm) swelling or tenderness ipsilateral to the side of injection. Systemic ARs: fever, headache, fatigue, myalgia, arthralgia, nausea/vomiting, and chills. Note, not all solicited ARs were considered adverse events (AEs). Investigator reviewed whether the solicited AR was also to be recorded as an AE. A Summary of serious AEs (SAEs) and nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.	7 days post-vaccination
Parts 1, 2, and 3: Number of Participants With Unsolicited AEs	An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. Any abnormal laboratory test result (hematology, clinical chemistry, or prothrombin time [PT]/partial thromboplastin time [PTT]) or other safety assessment (for example, electrocardiogram, radiological scan, vital sign measurement), including one that worsened from baseline and was considered clinically significant in the medical and scientific judgment of the Investigator was recorded as an AE. COVID-19/SARS-CoV-2 infections were considered clinical events for efficacy and not AEs. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section and presented by each dose group separately.	Up to 28 days post-vaccination
Parts 1, 2, and 3: Number of Participants With Serious Adverse Events (SAEs), AEs of Special Interest (AESIs), Medically Attended AEs (MAAEs), and AEs Leading to Discontinuation From Study	An SAE was defined as any AE that resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in disability, was a congenital anomaly/birth defect, or was an important medical event. AESIs for mRNA-1273 were identified based upon medical concepts that may be related to COVID-19 or were of interest in COVID-19 vaccine safety surveillance. An MAAE is an AE that led to an unscheduled visit to a healthcare practitioner. This included visits to a study site for unscheduled assessments and visits to healthcare practitioners external to the study site. COVID-19/SARS-CoV-2 infections were considered clinical events for efficacy and not AEs. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section and presented by each dose group separately.	Up to 2 years
Parts 1 and 2: Geometric Mean (GM) Value of Serum Pseudovirus Neutralizing Antibody ID50 Titers From Study mRNA-1273-P204 (P204) Vaccine Recipients at Day 57 Compared With Those From Young Adult (18 to 25 Years) Vaccine Recipients (Day 57) in Study P301	Antibody values reported as below lower limit of quantification (LLOQ) were replaced by 0.5*LLOQ and values greater than upper limit of quantification (ULOQ) were replaced by ULOQ if actual values were not available. LLOQ was 18.5 arbitrary units (AU)/milliliter (mL) and ULOQ was 45118 AU/mL for ID50 titer. Per-Protocol (PP) Immunogenicity Subset: all enrolled participants who received planned doses of the study vaccine per schedule, had baseline SARS-CoV-2 status, had baseline and Day 57 antibody assessment for analysis endpoint, complied with immunogenicity window based on 2nd injection timing; had negative reverse transcriptase polymerase chain reaction (RT-PCR) test for SARS-CoV-2 and negative serology test based on binding antibody (bAb) specific to SARS-CoV-2 nucleocapsid protein at baseline, not receiving highly active antiretroviral therapy (HAART) for participants with HIV; and had no major protocol deviations that impacted key or critical data.	Day 57 P204/Day 57 P301
Parts 2 and 3: GM Concentration of Serum Pseudovirus Neutralizing Antibody VAC62 From Study P204 Vaccine Recipients at Day 57 Compared With Those From Young Adult (18 to 25 Years of Age) Vaccine Recipients (Day 57) in Study P301	Antibody values reported as below LLOQ were replaced by 0.5*LLOQ and values >ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 10 AU/mL and ULOQ was 111433 AU/mL. PP Immunogenicity Subset: all enrolled participants who received planned doses of the study vaccine per schedule, had baseline SARS-CoV-2 status, had baseline and Day 57 antibody assessment, complied with immunogenicity window based on 2nd injection timing; had negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 nucleocapsid protein at baseline in Part 2, not receiving HAART in participants with HIV; and had no major protocol deviations that impacted key/critical data. Since the number of participants enrolled in Part 3 was substantially smaller than the planned sample size required for immunogenicity hypothesis testing after Dose 2 of mRNA-1273 25 μg primary series and after a 3rd dose of mRNA-1273 25 μg, the hypothesis testing was not performed.	Day 57 P204/Day 57 P301
Parts 1 and 2: Seroresponse Rate (SRR) For Serum Pseudovirus Neutralizing Antibody ID50 From Study P204 Vaccine Recipients at Day 57 Compared With Those From Young Adult (18 to 25 Years of Age) Vaccine Recipients (Day 57) in Study P301	Percentage of participants with seroresponse for pseudovirus neutralizing antibody ID50 are reported. Seroresponse: change from below LLOQ to equal above 4*LLOQ, or at least a 4-fold rise if baseline is ≥LLOQ. LLOQ=18.5 AU/mL and ULOQ=45118 AU/mL for ID50 titer. PP Immunogenicity Subset: all enrolled participants who received planned doses of study vaccine, had baseline SARS-CoV-2 status, had baseline and Day 57 antibody assessment, complied with immunogenicity window based on 2nd injection timing; had negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 at baseline, not receiving HAART; and had no major protocol deviations that impacted key/critical data. Since the number of participants enrolled in Part 3 was substantially smaller than the planned sample size required for immunogenicity hypothesis testing after Dose 2 of mRNA-1273 25 μg primary series and after a 3rd dose of mRNA-1273 25 μg, the hypothesis testing was not performed.	Day 57 P204/Day 57 P301
Parts 2 and 3: SRR For Serum Pseudovirus Neutralizing Antibody VAC62 From Study P204 Vaccine Recipients at Day 57 Compared With Those From Young Adult (18 to 25 Years of Age) Vaccine Recipients (Day 57) in Study P301	Percentage of participants with seroresponse for Pseudovirus Neutralizing Antibody VAC62 are reported. Seroresponse was defined as a change from below the LLOQ to equal above 4 * LLOQ, or at least a 4-fold rise if baseline is equal to or above the LLOQ. LLOQ was 10 and ULOQ AU/mL was 111433 AU/mL. PP Immunogenicity Subset: all enrolled participants who received planned doses of the study vaccine per schedule, had baseline SARS-CoV-2 status, had baseline and Day 57 antibody assessment for analysis endpoint, complied with immunogenicity window based on 2nd injection timing; had negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 nucleocapsid protein at baseline in Part 2, not receiving HAART in participants with HIV; and had no major protocol deviations that impacted key or critical data.	Day 57 P204/Day 57 P301
Parts 1 and 2: GM Concentration of Post-booster Dose Serum Pseudovirus Neutralizing Antibody VAC62 in Study P204 Compared With Post-primary Series (Post-Dose 2) in Young Adult (18 to 25 Years of Age) Vaccine Recipients in Study P301	Antibody values reported as below the LLOQ were replaced by 0.5*LLOQ and values greater than the ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 10 AU/mL and ULOQ was 111433 AU/mL. PP Immunogenicity Subset (Booster Dose Analysis): all enrolled participants who received 2 doses of planned doses of mRNA-1273 vaccination in Part 1 open-label phase or Part 2 blinded phase per schedule, received booster dose in Booster Dose Analysis, not receiving HAART in participants with HIV, had a negative SARS-CoV-2 status at baseline (pre-dose 1 of mRNA-1273), had BD-Day 29 Ab assessment for the analysis endpoint, no major protocol deviations that impacted key or critical data, and had not received off-study COVID-19 vaccination prior to BD-Day 29 visit.	BD-Day 29 P204/Day 57 P301
Part 3: GM Concentration of Post-third Dose Serum Pseudovirus Neutralizing Antibody VAC62 in Study P204 Compared With Post-primary Series (Post-Dose 2) in Young Adult (18 to 25 Years) Vaccine Recipients in Study P301	Antibody values reported as below the LLOQ were replaced by 0.5*LLOQ and values greater than the ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 10 AU/mL and ULOQ was 111433 AU/mL. PP Immunogenicity Subset (Third Dose Analysis): all enrolled participants who received first 2 doses of planned doses of mRNA-1273 vaccination in Part 3 open-label phase per schedule, received third dose in Third Dose Analysis, not receiving HAART in participants with HIV, had BD-Day 29 antibody assessment for the analysis endpoint, had no major protocol deviations that impacted key or critical data, and had not received off-study COVID-19 vaccination prior to BD-Day 29 visit. Since the number of participants enrolled in Part 3 was substantially smaller than the planned sample size required for immunogenicity hypothesis testing after Dose 2 of mRNA-1273 25 μg primary series and after a 3rd dose of mRNA-1273 25 μg, the hypothesis testing was not performed.	Third Dose-Day 29 P204/Day 57 P301
Parts 1 and 2: SRR for Post-booster Dose Serum Pseudovirus Neutralizing Antibody VAC62 From Baseline (Pre-Dose 1) Compared With Post-primary Series (Post-Dose 2) From Baseline (Pre-Dose 1) in Young Adult (18 to 25 Years) Vaccine Recipients in Study P301	Percentage of participants with seroresponse for Pseudovirus Neutralizing Antibody VAC62 are reported. Seroresponse was defined as a change from below the LLOQ to equal above 4 * LLOQ, or at least a 4-fold rise if baseline is equal to or above the LLOQ. LLOQ was 10 AU/mL and ULOQ was 111433 AU/mL. PP Immunogenicity Subset (Booster Dose Analysis): all enrolled participants who received 2 doses of planned doses of mRNA-1273 vaccination in Part 1 open-label phase or Part 2 blinded phase per schedule, received booster dose in Booster Dose Analysis, not receiving HAART in participants with HIV, had a negative SARS-CoV-2 status at baseline (pre-dose 1 of mRNA-1273), had BD-Day 29 Ab assessment for the analysis endpoint, no major protocol deviations that impacted key or critical data, and had not received off-study COVID-19 vaccination prior to BD-Day 29 visit.	BD-Day 29 P204/Day 57 P301
Part 3: SRR for Post-third Dose Serum Pseudovirus Neutralizing Antibody VAC62 From Baseline (Pre-Dose 1) Compared With Post-primary Series (Post-Dose 2) From Baseline (Pre-Dose 1) in Young Adult (18 to 25 Years) Vaccine Recipients in Study P301	Percentage of participants with seroresponse for Pseudovirus Neutralizing Antibody VAC62 are reported. Seroresponse was defined as a change from below the LLOQ to equal above 4 * LLOQ, or at least a 4-fold rise if baseline is equal to or above the LLOQ. LLOQ was 10 AU/mL and ULOQ was 111433 AU/mL. PP Immunogenicity Subset (Third Dose Analysis): all enrolled participants who received first 2 doses of planned doses of mRNA-1273 vaccination in Part 3 open-label phase per schedule, received third dose in Third Dose Analysis, not receiving HAART in participants with HIV were not receiving HAART, had BD-Day 29 antibody assessment for the analysis endpoint, had no major protocol deviations that impacted key or critical data, and had not received off-study COVID-19 vaccination prior to BD-Day 29 visit.	Third Dose-Day 29 P204/Day 57 P301

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Parts 1 and 2: GM Level of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) S Protein-specific Binding Antibody (bAb), as Measured by MesoScale Discovery (MSD) Electrochemiluminescence (ECL) Multiplex Assay on Days 1 and 57	GM level of SARSCOV2S2P immunoglobulin G (IgG) antibody VAC123/VAC72, as measured by ECL multiplex assay specific to SARS-CoV-2 spike protein is reported. Antibody values reported as <LLOQ were replaced by 0.5*LLOQ and values >ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 23 AU/mL and ULOQ was 14000000 AU/mL for VAC72. LLOQ was 69 AU/mL and ULOQ was 14400000 AU/mL for VAC123. PP Immunogenicity Subset: all enrolled participants who received planned doses of study vaccine per schedule, had baseline SARS-CoV-2 status, had baseline and Day 57 antibody assessment, complied with immunogenicity window based on 2nd injection timing; had negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 protein at baseline, not receiving HAART in participants with HIV; and had no major protocol deviations.	Day 1, Day 57 (1 month after Dose 2)
Parts 1 and 2: GM Level of SARS-CoV-2 S Protein-specific bAb, as Measured by MSD ECL Multiplex Assay on Baseline (Pre-dose 1), Day 57, Day 209, BD-Day 1, and BD-Day 29	GM level of SARSCOV2S2P IgG antibody VAC123/VAC72 is reported. Antibody values reported as <LLOQ were replaced by 0.5*LLOQ and values >ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 23 and ULOQ was 14000000 AU/mL for VAC72. LLOQ was 69 and ULOQ was 14400000 AU/mL for VAC123. PP Immunogenicity Subset (Booster Dose Analysis): all enrolled participants who received 2 doses of planned doses of mRNA-1273 in Part 1 open-label phase or Part 2 blinded phase per schedule, received booster dose in Booster Dose Analysis, , not receiving HAART in participants with HIV, had a negative SARS-CoV-2 status at baseline, had BD-Day 29 antibody assessment for the analysis endpoint, no major protocol deviations that impacted key or critical data, and had not receive off-study COVID-19 vaccination prior to BD-Day 29 visit.	Baseline (Pre-dose 1), Day 57, Day 209, BD-Day 1 (Pre-booster), BD-Day 29 (1 month after booster dose)
Part 3: GM Level of SARS-CoV-2 S Protein-specific bAb, as Measured by MSD ECL Multiplex Assay on Baseline (Pre-dose 1), Day 57, Third Dose-Day 1, Third Dose-Day 29, Third Dose-Day 181	GM level of SARSCOV2S2P IgG antibody against B.1.1.529 strain is reported. Antibody values reported as below the LLOQ were replaced by 0.5*LLOQ and values greater than the ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 102 and ULOQ was 1180000 AU/mL for VAC123. PP Immunogenicity Subset (Third Dose Analysis): all enrolled participants who received first 2 doses of planned doses of mRNA-1273 vaccination in Part 3 open-label phase per schedule, received third dose in Third Dose Analysis, participants with HIV were not receiving HAART, had BD-Day 29 antibody assessment for the analysis endpoint, had no major protocol deviations that impact key or critical data, and had not receive off-study COVID-19 vaccination prior to BD-Day 29 visit.	Baseline (Pre-dose 1), Day 57, Third Dose-Day 1, Third Dose-Day 29, Third Dose-Day 181
Parts 1 and 2: GM Value of SARS-CoV-2-specific Neutralizing Antibody ID50 Titers on Day 1 and Day 57	Antibody values reported as below LLOQ were replaced by 0.5*LLOQ and values greater than ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 18.5 AU/mL and ULOQ was 45118 AU/mL for ID50 titer. PP Immunogenicity Subset: all enrolled participants who received planned doses of the study vaccine per schedule, had baseline SARS-CoV-2 status, had baseline and Day 57 antibody assessment for analysis endpoint, complied with immunogenicity window based on 2nd injection timing; had negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 nucleocapsid protein at baseline, not receiving HAART in participants with HIV; and had no major protocol deviations that impacted key or critical data.	Day 1 and Day 57 (1 month after Dose 2)
Parts 2 and 3: GM Concentration of SARS-CoV-2-specific Neutralizing Antibody VAC62 on Day 1 and Day 57	Antibody values reported as below the LLOQ were replaced by 0.5*LLOQ and values greater than the ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 10 AU/mL and ULOQ was 111433 AU/mL. Data are reported per Baseline SARS-CoV-2 status: Negative and Positive. PP Immunogenicity Subset: all enrolled participants who received planned doses of the study vaccine per schedule, had baseline SARS-CoV-2 status, had baseline and Day 57 antibody assessment for analysis endpoint, complied with immunogenicity window based on 2nd injection timing; had negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 nucleocapsid protein at baseline in Part 2, not receiving HAART in participants with HIV; and had no major protocol deviations that impacted key or critical data.	Day 1 and Day 57 (1 month after Dose 2)
Parts 1 and 2: GM Concentration of Post-booster SARS-CoV-2-specific Neutralizing Antibody VAC62 on Baseline, Day 57, Day 209, BD-Day 1, and BD-Day 29	Antibody values reported as below the LLOQ were replaced by 0.5*LLOQ and values greater than the ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 10 AU/mL and ULOQ was 111433 AU/mL. PP Immunogenicity Subset (Booster Dose Analysis): all enrolled participants who received 2 doses of planned doses of mRNA-1273 vaccination in Part 1 open-label phase or Part 2 blinded phase per schedule, received booster dose in Booster Dose Analysis, not receiving HAART in participants with HIV, had a negative SARS-CoV-2 status at baseline (pre-dose 1 of mRNA-1273), had BD-Day 29 Ab assessment for the analysis endpoint, no major protocol deviations that impacted key or critical data, and had not received off-study COVID-19 vaccination prior to BD-Day 29 visit.	Baseline (Pre-Dose 1), Day 57 (1 month after Dose 2), Day 209 (6 months after Dose 2), BD-Day 1 (Pre-booster), and BD-Day 29 (1 month after booster dose or third dose)
Part 3: GM Concentration of Post-third Dose SARS-CoV-2-specific Neutralizing Antibody VAC62 on Baseline, Day 57, Third Dose-Day 1, Third Dose-Day 29, and Third Dose-Day 181	Antibody values reported as below the LLOQ were replaced by 0.5*LLOQ and values greater than the ULOQ were replaced by ULOQ if actual values were not available. LLOQ was 10 AU/mL and ULOQ was 111433 AU/mL. PP Immunogenicity Subset (Third Dose Analysis): all enrolled participants who received first 2 doses of planned doses of mRNA-1273 vaccination in Part 3 open-label phase per schedule, received third dose in Third Dose Analysis, not receiving HAART in participants with HIV, had BD-Day 29 antibody assessment for the analysis endpoint, had no major protocol deviations that impacted key or critical data, and had not received off-study COVID-19 vaccination prior to BD-Day 29 visit.	Baseline (Pre-Dose 1), Day 57 (1 month after Dose 2), Third Dose-Day 1 (at least 3 months or 6 months after Dose 2), Third Dose-Day 29 (1 month after third dose), and Third Dose-Day 181 (6 months after third dose)
Part 2: Number of Participants With SARS-CoV-2 Infection Including Symptomatic and Asymptomatic Infection (by Serology and/or RT-PCR)	SARS-CoV-2 infection was defined in participants with negative SARS-CoV-2 at baseline: bAb level against SARS-CoV-2 nucleocapsid protein negative at Day 1, that became positive (as measured by Roche Elecsys) postbaseline; OR positive RT-PCR postbaseline. PP Set for Efficacy included all enrolled participants who received planned doses of study drug per schedule, complied with the 2nd injection timing, had no major protocol deviations that impacted key or critical efficacy data, and had a negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 nucleocapsid protein at baseline.	14 days after second injection
Part 2: Number of Participants With Asymptomatic SARS-CoV-2 Infection, Measured by RT-PCR and/or bAb Levels Against SARS-CoV-2 Nucleocapsid Protein (by Roche Elecsys)	Asymptomatic SARS-CoV-2 infection was identified by absence of symptoms and infections as detected by RT-PCR or serology tests: Absence of COVID-19 symptoms AND at least 1 from following: bAb level against SARS-CoV-2 nucleocapsid protein negative at Day 1 that became positive post-baseline, OR positive RT-PCR test post-baseline. PP Set for Efficacy included all enrolled participants who received planned doses of study drug per schedule, complied with the 2nd injection timing, had no major protocol deviations that impacted key or critical efficacy data, and had a negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 nucleocapsid protein at baseline.	14 days after second injection
Part 2: Number of Participants With Occurrence of COVID-19 (Per US Centers for Disease Control and Prevention [CDC] Case Definition of COVID-19)	A COVID-19 case was identified as a positive post-baseline RT-PCR test result together with at least 1 of following systemic symptoms: fever (≥ 38 degrees Celsius [°C]/≥ 100.4 degree Fahrenheit [°F]) or chills, fatigue, headache, myalgia, nasal congestion or rhinorrhea, new loss of taste or smell, sore throat, abdominal pain, diarrhoea, nausea/vomiting, poor appetite/poor feeding; or at least 1 of following respiratory signs/symptoms: cough, shortness of breath or difficulty breathing. PP Set for Efficacy included all enrolled participants who received planned doses of study drug per schedule, complied with the 2nd injection timing, had no major protocol deviations that impacted key or critical efficacy data, and had a negative RT-PCR test for SARS-CoV-2 and negative serology test based on bAb specific to SARS-CoV-2 nucleocapsid protein at baseline.	14 days after second injection

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Deaths Related to Study Drug	A death that occurred during the study or that came to the attention of the investigator during the study was reported to the Sponsor, whether or not it was considered related to study drug. The investigator assessed causality (that is, whether there is a reasonable possibility that the study drug caused the death). The relationship was characterized using the following classifications: Not related: There was not a reasonable possibility of a relationship to the study drug. The temporal sequence of the death relative to administration of the study drug was not reasonable AND/OR the death was more likely explained by a cause other than the study drug. Related: There was a reasonable possibility of a relationship to the study drug. There was evidence of exposure to the study drug. The temporal sequence of the death relative to the administration of the study drug was reasonable. The death was more likely explained by the study drug than by another cause.	Up to 2 years

Collaborators and Investigators

• Sponsor: ModernaTX, Inc.

Publications and helpful links

General Publications

• Anderson EJ, Creech CB, Berthaud V, Piramzadian A, Johnson KA, Zervos M, Garner F, Griffin C, Palanpurwala K, Turner M, Gerber J, Bennett RL, Ali K, Ampajwala M, Berman G, Nayak J, Chronis C, Rizzardi B, Muller WJ, Smith CA, Fuchs G, Hsia D, Tomassini JE, DeLucia D, Reuter C, Kuter B, Zhao X, Deng W, Zhou H, Ramirez Schrempp D, Hautzinger K, Girard B, Slobod K, McPhee R, Pajon R, Aunins A, Das R, Miller JM, Schnyder Ghamloush S; KidCOVE Study Group. Evaluation of mRNA-1273 Vaccine in Children 6 Months to 5 Years of Age. N Engl J Med. 2022 Nov 3;387(18):1673-1687. doi: 10.1056/NEJMoa2209367. Epub 2022 Oct 19.
• Creech CB, Anderson E, Berthaud V, Yildirim I, Atz AM, Melendez Baez I, Finkelstein D, Pickrell P, Kirstein J, Yut C, Blair R, Clifford RA, Dunn M, Campbell JD, Montefiori DC, Tomassini JE, Zhao X, Deng W, Zhou H, Ramirez Schrempp D, Hautzinger K, Girard B, Slobod K, McPhee R, Pajon R, Das R, Miller JM, Schnyder Ghamloush S; KidCOVE Study Group. Evaluation of mRNA-1273 Covid-19 Vaccine in Children 6 to 11 Years of Age. N Engl J Med. 2022 May 26;386(21):2011-2023. doi: 10.1056/NEJMoa2203315. Epub 2022 May 11.
• Lynch LR, Clifford H, Ko R, Hache M, Sun W. Primer of COVID-19 Vaccines for the Perioperative Physician. J Neurosurg Anesthesiol. 2022 Jan 1;34(1):101-106. doi: 10.1097/ANA.0000000000000802.

Helpful Links

• Click here to access the website, http://www.kidcovestudy.com, for additional information for the study, such as Study Overview, Participation, Site Locations, along with contact numbers for each location for the study.

Study record dates

Study Major Dates

• Study Start (Actual): March 15, 2021
• Primary Completion (Actual): March 15, 2024
• Study Completion (Actual): March 15, 2024

Study Registration Dates

• First Submitted: March 11, 2021
• First Submitted That Met QC Criteria: March 11, 2021
• First Posted (Actual): March 15, 2021

Study Record Updates

• Last Update Posted (Actual): June 13, 2025
• Last Update Submitted That Met QC Criteria: May 22, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Keywords: SARS-CoV-2; Coronavirus; COVID-19; SARS-CoV-2 Vaccine; Virus Diseases; Moderna; Messenger RNA; COVID-19 Vaccine; mRNA-1273 vaccine; mRNA-1273
• Other Study ID Numbers: mRNA-1273-P204

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No