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    Clinical Trial Results:
    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

    Summary
    EudraCT number
    		 2024-000165-25
    Trial protocol
    		 Outside EU/EEA  
    Global end of trial date
    20 Oct 2025

    Results information
    Results version number
    		 v1(current)
    This version publication date
    06 May 2026
    First version publication date
    06 May 2026
    Other versions

    Trial information

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    Trial identification
    Sponsor protocol code
    mRNA-1273-P306
    Additional study identifiers
    ISRCTN number
    		 -
    US NCT number
    		 NCT05436834
    WHO universal trial number (UTN)
    		 -
    Sponsors
    Sponsor organisation name
    ModernaTX, Inc.
    Sponsor organisation address
    325 Binney Street, Cambridge, MA, United States, 02142
    Public contact
    Moderna Clinical Trials Support Center, ModernaTX, Inc., 1 866-663-3762, WeCareClinicalTrials@modernatx.com
    Scientific contact
    Moderna Clinical Trials Support Center, ModernaTX, Inc., 1 866-663-3762, WeCareClinicalTrials@modernatx.com
    Paediatric regulatory details
    Is trial part of an agreed paediatric investigation plan (PIP)
    No
    Does article 45 of REGULATION (EC) No 1901/2006 apply to this trial?
    No
    Does article 46 of REGULATION (EC) No 1901/2006 apply to this trial?
    Yes
    Results analysis stage
    Analysis stage
    Final
    Date of interim/final analysis
    20 Oct 2025
    Is this the analysis of the primary completion data?
    Yes
    Primary completion date
    20 Oct 2025
    Global end of trial reached?
    Yes
    Global end of trial date
    20 Oct 2025
    Was the trial ended prematurely?
    No
    General information about the trial
    Main objective of the trial
    This study evaluated 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 evaluated 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).
    Protection of trial subjects
    This study was conducted in accordance with the protocol and consensus ethical principles derived from international guidelines including the Declaration of Helsinki, and Council for International Organizations of Medical Sciences (CIOMS) International Ethical Guidelines, applicable International Council for Harmonisation (ICH) Good Clinical Practice (GCP) guidelines, and other applicable laws and regulatory requirements.
    Background therapy
    		 -
    Evidence for comparator
    		 -
    Actual start date of recruitment
    21 Jun 2022
    Long term follow-up planned
    Yes
    Long term follow-up rationale
    		 Safety
    Long term follow-up duration
    		 12 Months
    Independent data monitoring committee (IDMC) involvement?
    Yes
    Population of trial subjects
    Number of subjects enrolled per country
    Country: Number of subjects enrolled
    United States: 1802
    Worldwide total number of subjects
    1802
    EEA total number of subjects
    0
    Number of subjects enrolled per age group
    In utero
    0
    Preterm newborn - gestational age < 37 wk
    0
    Newborns (0-27 days)
    0
    Infants and toddlers (28 days-23 months)
    677
    Children (2-11 years)
    1125
    Adolescents (12-17 years)
    0
    Adults (18-64 years)
    0
    From 65 to 84 years
    0
    85 years and over
    0

    Subject disposition

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    Recruitment
    Recruitment details
    		 Study mRNA-1273-P306 (P306): Part 1 enrolled vaccine-naïve participants; Part 2 enrolled participants who had previously been vaccinated with mRNA-1273 primary series; Part 3 enrolled participants who had previously been vaccinated with an authorized/approved COVID-19 vaccine; Part 4 enrolled SARS-CoV-2 vaccine-naïve participants.

    Pre-assignment
    Screening details
    		 Four participants were enrolled in the study but were not dosed and data are not included for these participants. Data from participants from study mRNA-1273-P204 (P204, NCT04796896) of the same age group, vaccinated with a mRNA-1273 primary series were used for comparison of immune response.

    Period 1
    Period 1 title
    Overall Study (overall period)
    Is this the baseline period?
    		 Yes
    Allocation method
    Non-randomised - controlled
    Blinding used
    		 Not blinded

    Arms
    Are arms mutually exclusive
    Yes

    Arm title
    		 Part 1: mRNA-1273.214
    Arm description
    		 Participants, 6 months to <6 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 micrograms (μg) intramuscular (IM) injections of mRNA-1273.214 vaccine as a 2-dose series on Day 1 and Day 29.
    Arm type
    		 Experimental

    Investigational medicinal product name
    mRNA-1273.214
    Investigational medicinal product code
    Other name
    Pharmaceutical forms
    Sterile concentrate
    Routes of administration
    Intramuscular use
    Dosage and administration details
    mRNA-1273.214 was administered per dose and schedule specified in the arm description.

    Arm title
    		 Part 2: mRNA-1273.214
    Arm description
    		 Participants, 6 months to <6 years of age, who had previously been vaccinated with a mRNA-1273 primary series, received a single IM 10 µg booster dose (BD) of mRNA-1273.214 vaccine at least 4 months after completion of the mRNA-1273 primary series.
    Arm type
    		 Experimental

    Investigational medicinal product name
    mRNA-1273.214
    Investigational medicinal product code
    Other name
    Pharmaceutical forms
    Sterile concentrate
    Routes of administration
    Intramuscular use
    Dosage and administration details
    mRNA-1273.214 was administered per dose and schedule specified in the arm description.

    Arm title
    		 Part 3: mRNA-1273.815
    Arm description
    		 Participants, 6 months to <6 years of age, who had previously been vaccinated with an authorized/approved COVID-19 vaccine, received a single IM 25 μg BD of mRNA-1273.815 vaccine on BD Day 1, at least 4 months after the last dose of a COVID-19 vaccine.
    Arm type
    		 Experimental

    Investigational medicinal product name
    mRNA-1273.815
    Investigational medicinal product code
    Other name
    Pharmaceutical forms
    Sterile concentrate
    Routes of administration
    Intramuscular use
    Dosage and administration details
    mRNA-1273.815 was administered per dose and schedule specified in the arm description.

    Arm title
    		 Part 4: mRNA-1273.815 Cohort A
    Arm description
    		 Participants, 2 to <5 years of age, who had not been previously vaccinated against SARS-CoV-2, received a single 25 μg IM injection of mRNA-1273.815 vaccine on Day 1.
    Arm type
    		 Experimental

    Investigational medicinal product name
    mRNA-1273.815
    Investigational medicinal product code
    Other name
    Pharmaceutical forms
    Sterile concentrate
    Routes of administration
    Intramuscular use
    Dosage and administration details
    mRNA-1273.815 was administered per dose and schedule specified in the arm description.

    Arm title
    		 Part 4: mRNA-1273.815 Cohort B
    Arm description
    		 Participants, 6 months to <2 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injections of mRNA-1273.815 vaccine as a 2-dose series on Day 1 and Day 29.
    Arm type
    		 Experimental

    Investigational medicinal product name
    mRNA-1273.815
    Investigational medicinal product code
    Other name
    Pharmaceutical forms
    Sterile concentrate
    Routes of administration
    Intramuscular use
    Dosage and administration details
    mRNA-1273.815 was administered per dose and schedule specified in the arm description.

    Number of subjects in period 1
    		Part 1: mRNA-1273.214 Part 2: mRNA-1273.214 Part 3: mRNA-1273.815 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B
    Started
    391
    539
    274
    199
    399
    Received at Least 1 Dose of Study Drug
    391
    539
    274
    199
    399
    Solicited Safety Set
    391
    539
    271
    199
    399
    Per-protocol Immunogenicity Set (PPIS)
    304 [1]
    468 [2]
    252 [3]
    148 [4]
    352 [5]
    Safety Set
    391
    539
    274
    199
    399
    PPIS-Pos
    240 [6]
    149 [7]
    211 [8]
    143 [9]
    276 [10]
    PPIS-Neg
    64 [11]
    319 [12]
    41 [13]
    5 [14]
    76 [15]
    Completed
    318
    493
    267
    197
    383
    Not completed
    73
    46
    7
    2
    16
         Consent withdrawn by subject
    18
    21
    4
    -
    10
         Physician decision
    3
    -
    -
    -
    -
         Protocol Deviation
    1
    -
    -
    2
    -
         Other than Specified
    8
    -
    -
    -
    -
         Lost to follow-up
    43
    25
    3
    -
    6
    Notes
    [1] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [2] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [3] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [4] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [5] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [6] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [7] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [8] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [9] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [10] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [11] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [12] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [13] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [14] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population
    [15] - The number of subjects at this milestone seems inconsistent with the number of subjects in the arm. It is expected that the number of subjects will be greater than, or equal to the number that completed, minus those who left.
    Justification: Analysis set population

    Baseline characteristics

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    Baseline characteristics reporting groups
    Reporting group title
    Part 1: mRNA-1273.214
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 micrograms (μg) intramuscular (IM) injections of mRNA-1273.214 vaccine as a 2-dose series on Day 1 and Day 29.

    Reporting group title
    Part 2: mRNA-1273.214
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had previously been vaccinated with a mRNA-1273 primary series, received a single IM 10 µg booster dose (BD) of mRNA-1273.214 vaccine at least 4 months after completion of the mRNA-1273 primary series.

    Reporting group title
    Part 3: mRNA-1273.815
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had previously been vaccinated with an authorized/approved COVID-19 vaccine, received a single IM 25 μg BD of mRNA-1273.815 vaccine on BD Day 1, at least 4 months after the last dose of a COVID-19 vaccine.

    Reporting group title
    Part 4: mRNA-1273.815 Cohort A
    Reporting group description
    		 Participants, 2 to <5 years of age, who had not been previously vaccinated against SARS-CoV-2, received a single 25 μg IM injection of mRNA-1273.815 vaccine on Day 1.

    Reporting group title
    Part 4: mRNA-1273.815 Cohort B
    Reporting group description
    		 Participants, 6 months to <2 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injections of mRNA-1273.815 vaccine as a 2-dose series on Day 1 and Day 29.

    Reporting group values
    		 Part 1: mRNA-1273.214 Part 2: mRNA-1273.214 Part 3: mRNA-1273.815 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B Total
    Number of subjects
    		 391 539 274 199 399 1802
    Age Categorical
    Units: Subjects
        In utero
        Preterm newborn infants (gestational age < 37 wks)
        Newborns (0-27 days)
        Infants and toddlers (28 days-23 months)
        Children (2-11 years)
        Adolescents (12-17 years)
        Adults (18-64 years)
        From 65-84 years
        85 years and over
    Age Continuous
    Units: years
        arithmetic mean (standard deviation)
    		 2.51 ( 1.488 ) 2.73 ( 1.277 ) 3.06 ( 1.319 ) 2.91 ( 0.860 ) 0.89 ( 0.158 ) -
    Gender Categorical
    Units: Subjects
        Female
    		 189 263 138 99 191 880
        Male
    		 202 276 136 100 208 922

    End points

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    End points reporting groups
    Reporting group title
    Part 1: mRNA-1273.214
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 micrograms (μg) intramuscular (IM) injections of mRNA-1273.214 vaccine as a 2-dose series on Day 1 and Day 29.

    Reporting group title
    Part 2: mRNA-1273.214
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had previously been vaccinated with a mRNA-1273 primary series, received a single IM 10 µg booster dose (BD) of mRNA-1273.214 vaccine at least 4 months after completion of the mRNA-1273 primary series.

    Reporting group title
    Part 3: mRNA-1273.815
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had previously been vaccinated with an authorized/approved COVID-19 vaccine, received a single IM 25 μg BD of mRNA-1273.815 vaccine on BD Day 1, at least 4 months after the last dose of a COVID-19 vaccine.

    Reporting group title
    Part 4: mRNA-1273.815 Cohort A
    Reporting group description
    		 Participants, 2 to <5 years of age, who had not been previously vaccinated against SARS-CoV-2, received a single 25 μg IM injection of mRNA-1273.815 vaccine on Day 1.

    Reporting group title
    Part 4: mRNA-1273.815 Cohort B
    Reporting group description
    		 Participants, 6 months to <2 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injections of mRNA-1273.815 vaccine as a 2-dose series on Day 1 and Day 29.

    Subject analysis set title
    Part 1: mRNA-1273.214
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 6 months to <6 years of age, who had not been previously vaccinated against SARS-CoV-2, were to receive 25 μg IM injections of mRNA-1273.214 vaccine as a 2-dose series on Day 1 and Day 29.

    Subject analysis set title
    Part 1: mRNA-1273.214 First Injection
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 6 months to <6 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injection of mRNA-1273.214 vaccine on Day 1.

    Subject analysis set title
    Part 1: mRNA-1273.214 Second Injection
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 6 months to <6 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injection of mRNA-1273.214 vaccine on Day 29.

    Subject analysis set title
    Part 2: mRNA-1273.214
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 6 months to <6 years of age, who had previously been vaccinated with a mRNA-1273 primary series, received a single IM 10 μg BD of mRNA-1273.214 vaccine at least 4 months after completion of the mRNA-1273 primary series.

    Subject analysis set title
    Part 3: mRNA-1273.815
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 6 months to <6 years of age, who had previously been vaccinated with an authorized/approved COVID-19 vaccine, received a single IM 25 μg BD of mRNA-1273.815 vaccine on BD Day 1, at least 4 months after the last dose of a COVID-19 vaccine.

    Subject analysis set title
    Part 4: mRNA-1273.815 Cohort A
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 2 to <5 years of age, who had not been previously vaccinated against SARS-CoV-2, received a single 25 μg IM injection of mRNA-1273.815 vaccine on Day 1.

    Subject analysis set title
    Part 4: mRNA-1273.815 Cohort B
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 6 months to <2 years of age, who had not been previously vaccinated against SARS-CoV-2, were to receive 25 μg IM injections of mRNA-1273.815 vaccine as a 2-dose series on Day 1 and Day 29.

    Subject analysis set title
    Part 4: mRNA-1273.815 Cohort B First Injection
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 6 months to <2 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injection of mRNA-1273.815 vaccine on Day 1.

    Subject analysis set title
    Part 4: mRNA-1273.815 Cohort B Second Injection
    Subject analysis set type
    		 Safety analysis
    Subject analysis set description
    Participants, 6 months to <2 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injection of mRNA-1273.815 vaccine on Day 29.

    Subject analysis set title
    P204 mRNA-1273 Primary Series
    Subject analysis set type
    		 Per protocol
    Subject analysis set description
    Participants received 25 μg mRNA-1273 25 μg primary series in Study P204.

    Primary: Parts 1, 2, 3, 4 Cohort A, 4 Cohort B: Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs)

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    End point title
    		 Parts 1, 2, 3, 4 Cohort A, 4 Cohort B: Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs) [1]
    End point description
    Solicited AR were reported by participants daily via electronic diary. Solicited local (injection site pain, injection site erythema [redness]), injection site swelling/induration [hardness], axillary [or groin] swelling or tenderness) and systemic AR (fever [all age groups], irritability/crying, sleepiness, and loss of appetite [6-36 months], and headache, fatigue, myalgia, arthralgia, nausea/vomiting, and chills [37 months-<6 years] and assessed by toxicity grading (Grades 0-4) modified from Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in Preventative Vaccine Clinical Trials. Lower score indicated lower severity. Solicited Safety Set: participants who received at least 1 dose of study drug and contributed any solicited AR data.
    End point type
    Primary
    End point timeframe
    Up to 7 days after any injection
    Notes
    [1] - No statistical analyses have been specified for this primary end point. It is expected there is at least one statistical analysis for each primary end point.
    Justification: Date reported for applicable reporting arms.
    End point values
    		 Part 1: mRNA-1273.214 First Injection Part 1: mRNA-1273.214 Second Injection Part 2: mRNA-1273.214 Part 3: mRNA-1273.815 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B First Injection Part 4: mRNA-1273.815 Cohort B Second Injection
    Number of subjects analysed
    391
    377
    539
    271
    199
    399
    386
    Units: participants
        Grade 1
    153
    132
    253
    92
    60
    106
    84
        Grade 2
    56
    61
    99
    37
    13
    34
    31
        Grade 3
    7
    11
    19
    17
    9
    12
    15
        Grade 4
    0
    1
    0
    0
    0
    0
    0
        Any AR
    216
    205
    371
    146
    82
    152
    130
    No statistical analyses for this end point

    Primary: Parts 1, 2, 3, 4 Cohort A, 4 Cohort B: Number of Participants With Unsolicited Adverse Events (AEs) After Any Injection

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    End point title
    		 Parts 1, 2, 3, 4 Cohort A, 4 Cohort B: Number of Participants With Unsolicited Adverse Events (AEs) After Any Injection [2]
    End point description
    An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. Abnormal laboratory test result or other safety assessment, including one that worsened from baseline and considered clinically significant by investigator was recorded as an AE. Active surveillance for COVID-19 was included in Parts 1 and 2, but not in Parts 3 and 4, so COVID-19/SARS-CoV-2 infections were considered clinical events and not AEs in Parts 1 and 2, and considered as AEs in Parts and Part 4. Summary of SAEs and nonserious AEs, regardless of causality, are located in AE section. Safety Set: received at least 1 dose of study drug.
    End point type
    Primary
    End point timeframe
    28 days after any injection
    Notes
    [2] - No statistical analyses have been specified for this primary end point. It is expected there is at least one statistical analysis for each primary end point.
    Justification: Date reported for applicable reporting arms.
    End point values
    		 Part 1: mRNA-1273.214 Part 2: mRNA-1273.214 Part 3: mRNA-1273.815 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B
    Number of subjects analysed
    391
    539
    274
    199
    399
    Units: participants
    138
    112
    49
    39
    207
    No statistical analyses for this end point

    Primary: Parts 1, 2, 3, 4 Cohort A, 4 Cohort B: Number of Participants with Serious AEs (SAEs), Medically Attended AEs (MAAEs), AEs of Special Interest (AESIs), and AEs Leading to Discontinuation from Participation in the Study

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    End point title
    		 Parts 1, 2, 3, 4 Cohort A, 4 Cohort B: Number of Participants with Serious AEs (SAEs), Medically Attended AEs (MAAEs), AEs of Special Interest (AESIs), and AEs Leading to Discontinuation from Participation in the Study [3]
    End point description
    SAE: AE resulting in death, life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in disability/permanent damage, a congenital anomaly/birth defect, or important medical event. MAAE: AE that led to unscheduled visit to doctor included visits to a site for unscheduled assessments. AESI identified based on medical concepts that may be related to COVID-19 or were of interest in COVID-19 vaccine safety surveillance. Active surveillance for COVID-19 was included in Parts 1 and 2, but not in Parts 3 and 4, so COVID-19/SARS-CoV-2 infections were considered clinical events and not AEs in Parts 1 and 2, and considered as AEs in Parts and Part 4. Safety Set: received at least 1 dose of study drug.
    End point type
    Primary
    End point timeframe
    Up to Day 394
    Notes
    [3] - No statistical analyses have been specified for this primary end point. It is expected there is at least one statistical analysis for each primary end point.
    Justification: Date reported for applicable reporting arms.
    End point values
    		 Part 1: mRNA-1273.214 Part 2: mRNA-1273.214 Part 3: mRNA-1273.815 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B
    Number of subjects analysed
    391
    539
    274
    199
    399
    Units: participants
        SAE
    10
    9
    5
    0
    13
        MAAE
    242
    310
    66
    31
    172
        AESI
    4
    4
    2
    0
    1
        AEs Leading to Discontinuation from the Study
    0
    0
    0
    0
    0
    No statistical analyses for this end point

    Primary: Part 1 Geometric Mean Concentration (GMC) of Pseudovirus Neutralizing Antibody (nAb) Against Omicron BA.1 after mRNA-1273.214 Administration Compared with GMC After P204 mRNA-1273 Primary Series of Same Age Group

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    End point title
    		 Part 1 Geometric Mean Concentration (GMC) of Pseudovirus Neutralizing Antibody (nAb) Against Omicron BA.1 after mRNA-1273.214 Administration Compared with GMC After P204 mRNA-1273 Primary Series of Same Age Group
    End point description
    Measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC122 for BA.1 [B.1.1.529], LLOQ: 8 arbitrary units (AU)/milliliter (mL), ULOQ: 24503 AU/mL. Analysis Set: P306 Part 1 PPIS and P204 PPIS was used for comparison of immune response. PPIS: all participants, regardless of Baseline SARS-CoV-2 status, who had baseline and P306 Day 57/P204 Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint. n = participants evaluable for the specified category.
    End point type
    Primary
    End point timeframe
    P306 Day 57/P204 Day 57
    End point values
    		 Part 1: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    300
    607
    Units: AU/mL
        geometric mean (confidence interval 95%)
    3949.4 (3567.3 to 4372.4)
    77.7 (72.3 to 83.5)
    Statistical analysis title
    		 Statistical Analysis Test 1
    Comparison groups
    P204 mRNA-1273 Primary Series v Part 1: mRNA-1273.214
    Number of subjects included in analysis
    907
    Analysis specification
    Pre-specified
    Analysis type
    		 superiority [4]
    Method
    		 ANCOVA
    Parameter type
    		 Geometric mean ratio (GMR)
    Point estimate
    50.829
    Confidence interval
         level
    		 95%
         sides
    2-sided
         lower limit
    		 44.884
         upper limit
    		 57.562
    Notes
    [4] - Superiority criterion: lower bound of 95% CI of GMR >1.0

    Primary: Part 1 Geometric Mean Concentration (GMC) of Pseudovirus Neutralizing Antibody (nAb) Against Ancestral SARS-CoV-2 (D614G) after mRNA-1273.214 Administration Compared with GMC After P204 mRNA-1273 Primary Series of Same Age Group

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    End point title
    		 Part 1 Geometric Mean Concentration (GMC) of Pseudovirus Neutralizing Antibody (nAb) Against Ancestral SARS-CoV-2 (D614G) after mRNA-1273.214 Administration Compared with GMC After P204 mRNA-1273 Primary Series of Same Age Group
    End point description
    Measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC62 for D614G [original strain], LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL. Analysis Set: P306 Part 1 PPIS and P204 PPIS was used for comparison of immune response. PPIS: all participants, regardless of Baseline SARS-CoV-2 status, who had baseline and P306 Day 57/P204 Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint. n = participants evaluable for the specified category.
    End point type
    Primary
    End point timeframe
    P306 Day 57/P204 Day 57
    End point values
    		 Part 1: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    301
    594
    Units: AU/mL
        geometric mean (confidence interval 95%)
    2068.2 (1859.3 to 2300.6)
    1732.5 (1606.0 to 1868.9)
    Statistical analysis title
    		 Statistical Analysis Test 1
    Comparison groups
    Part 1: mRNA-1273.214 v P204 mRNA-1273 Primary Series
    Number of subjects included in analysis
    895
    Analysis specification
    Pre-specified
    Analysis type
    		 non-inferiority [5]
    Method
    		 ANCOVA
    Parameter type
    		 GMR
    Point estimate
    1.194
    Confidence interval
         level
    		 95%
         sides
    2-sided
         lower limit
    		 1.048
         upper limit
    		 1.36
    Notes
    [5] - Noninferiority criterion: lower bound of 95% CI of GMR >0.667

    Primary: Part 2: GMC of the Pseudovirus nAb Against Omicron BA.1 After mRNA-1273.214 Administration at BD-Day 29 Compared with GMC After P204 mRNA-1273 Primary Series of Same Age Group

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    End point title
    		 Part 2: GMC of the Pseudovirus nAb Against Omicron BA.1 After mRNA-1273.214 Administration at BD-Day 29 Compared with GMC After P204 mRNA-1273 Primary Series of Same Age Group
    End point description
    Pseudovirus nAb measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC122 for BA.1 [B.1.1.529], LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL). Analysis Set: P306 Part 2 PPIS-Neg and P204 PPIS-Neg was used for comparison of immune response. PPIS-Neg: all participants with negative Baseline SARS-CoV-2 status, who had baseline and P306 BD-Day 29/P204 Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint. n = participants evaluable for specified category.
    End point type
    Primary
    End point timeframe
    P306 BD-Day 29/P204 Day 57
    End point values
    		 Part 2: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    316
    567
    Units: AU/mL
        geometric mean (confidence interval 95%)
    805.2 (731.2 to 886.8)
    66.6 (62.0 to 71.6)
    Statistical analysis title
    		 Statistical Analysis 1
    Comparison groups
    Part 2: mRNA-1273.214 v P204 mRNA-1273 Primary Series
    Number of subjects included in analysis
    883
    Analysis specification
    Pre-specified
    Analysis type
    		 superiority [6]
    Method
    		 ANCOVA
    Parameter type
    		 GMR
    Point estimate
    12.085
    Confidence interval
         level
    		 95%
         sides
    2-sided
         lower limit
    		 10.715
         upper limit
    		 13.631
    Notes
    [6] - Superiority criterion: lower bound of 95% CI of GMR >1.0

    Primary: Part 2: GMC of the Pseudovirus nAb Against Ancestral SARS-CoV-2 (D614G) After mRNA-1273.214 Administration at BD-Day 29 Compared with GMC After P204 mRNA-1273 Primary Series of Same Age Group

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    End point title
    		 Part 2: GMC of the Pseudovirus nAb Against Ancestral SARS-CoV-2 (D614G) After mRNA-1273.214 Administration at BD-Day 29 Compared with GMC After P204 mRNA-1273 Primary Series of Same Age Group
    End point description
    Pseudovirus nAb measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC62 for D614G [original strain], LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL). Analysis Set: P306 Part 2 PPIS-Neg and P204 PPIS-Neg was used for comparison of immune response. PPIS-Neg: all participants with negative Baseline SARS-CoV-2 status, who had baseline and P306 BD-Day 29/P204 Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint. n = participants evaluable for specified category.
    End point type
    Primary
    End point timeframe
    P306 BD-Day 29/P204 Day 57
    End point values
    		 Part 2: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    316
    557
    Units: AU/mL
        geometric mean (confidence interval 95%)
    4754.7 (4346.9 to 5200.7)
    1559.4 (1457.6 to 1668.4)
    Statistical analysis title
    		 Statistical Analysis 1
    Comparison groups
    Part 2: mRNA-1273.214 v P204 mRNA-1273 Primary Series
    Number of subjects included in analysis
    873
    Analysis specification
    Pre-specified
    Analysis type
    		 non-inferiority [7]
    Method
    		 ANCOVA
    Parameter type
    		 GMR
    Point estimate
    3.049
    Confidence interval
         level
    		 95%
         sides
    2-sided
         lower limit
    		 2.725
         upper limit
    		 3.411
    Notes
    [7] - Noninferiority criterion: lower bound of 95% CI of GMR >0.667

    Primary: Part 2: Seroresponse Rate (SRR) Against Omicron BA.1 After mRNA-1273.214 at BD-29 Compared with SRR after P204 mRNA-1273 Primary Series of Same Age Group

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    End point title
    		 Part 2: Seroresponse Rate (SRR) Against Omicron BA.1 After mRNA-1273.214 at BD-29 Compared with SRR after P204 mRNA-1273 Primary Series of Same Age Group
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse relative to baseline (pre-Dose of primary series) SRR at a participant level was defined as a change from Baseline (pre-Dose 1 of P204 primary series) below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC122 for BA.1 [B.1.1.529], LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL). Analysis Set: P306 Part 2 PPIS-Neg and P204 PPIS-Neg was used for comparison of immune response. PPIS-Neg: all participants with negative Baseline SARS-CoV-2 status, who had baseline and P306 BD-Day 29/P204 Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint. n = participants evaluable for specified category.
    End point type
    Primary
    End point timeframe
    P306 BD-Day 29/P204 Day 57
    End point values
    		 Part 2: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    312
    562
    Units: percentage of participants
        number (confidence interval 95%)
    99.0 (97.2 to 99.8)
    84.9 (81.6 to 87.7)
    Statistical analysis title
    		 Statistical Analysis 1
    Comparison groups
    Part 2: mRNA-1273.214 v P204 mRNA-1273 Primary Series
    Number of subjects included in analysis
    874
    Analysis specification
    Pre-specified
    Analysis type
    		 non-inferiority [8]
    Method
    		 Miettinen-Nurminen Score
    Parameter type
    		 SRR difference
    Point estimate
    14.2
    Confidence interval
         level
    		 95%
         sides
    2-sided
         lower limit
    		 11.1
         upper limit
    		 17.5
    Notes
    [8] - Noninferiority: Lower bound of the 95% CI of the SRR difference >-5% with noninferiority margin of 5%

    Primary: Part 4: GMC of the Pseudovirus nAb Against SARS-CoV-2 VOC (Omicron XBB.1.5) After a Single Dose of mRNA-1273.815 (Cohort A) Compared with GMC after 2 Doses of mRNA-1273.815 (Cohort B)

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    End point title
    		 Part 4: GMC of the Pseudovirus nAb Against SARS-CoV-2 VOC (Omicron XBB.1.5) After a Single Dose of mRNA-1273.815 (Cohort A) Compared with GMC after 2 Doses of mRNA-1273.815 (Cohort B)
    End point description
    Pseudovirus nAb measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC150 for XBB.1.5 AU/mL, LLOQ: 38 AU/mL, ULOQ: 6960 AU/mL). Analysis Set: P306 Part 4 Cohort A PPIS-Pos and P306 Part 4 Cohort B PPIS-Neg was used for comparison of immune response. PPIS-Pos: all participants who were SARS-CoV-2 positive at baseline who had baseline and Day 29 Cohort A/Day 57 Cohort B Ab assessments and had no major protocol deviations that impacted key or critical data. PPIS-Neg: all participants who were SARS-CoV-2 negative at baseline, who had baseline Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Primary
    End point timeframe
    Day 29 Cohort A/Day 57 Cohort B
    End point values
    		 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B
    Number of subjects analysed
    143
    76
    Units: AU/mL
        geometric mean (confidence interval 95%)
    2074.1 (1637.8 to 2626.7)
    1736.3 (1255.8 to 2400.6)
    Statistical analysis title
    		 Statistical Analysis 1
    Statistical analysis description
    Cohort A versus Cohort B
    Comparison groups
    Part 4: mRNA-1273.815 Cohort A v Part 4: mRNA-1273.815 Cohort B
    Number of subjects included in analysis
    219
    Analysis specification
    Pre-specified
    Analysis type
    		 non-inferiority [9]
    Method
    		 ANCOVA
    Parameter type
    		 GMR
    Point estimate
    1.195
    Confidence interval
         level
    		 95%
         sides
    2-sided
         lower limit
    		 0.8
         upper limit
    		 1.784
    Notes
    [9] - Noninferiority criterion: lower bound of the 95% CI >0.667

    Primary: Part 2: SRR Against Ancestral SARS-CoV-2 (D614G) After mRNA-1273.214 at BD-29 Compared with SRR after P204 mRNA-1273 Primary Series of Same Age Group

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    End point title
    		 Part 2: SRR Against Ancestral SARS-CoV-2 (D614G) After mRNA-1273.214 at BD-29 Compared with SRR after P204 mRNA-1273 Primary Series of Same Age Group
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse relative to baseline (pre-Dose of primary series) SRR at a participant level was defined as a change from Baseline (pre-Dose 1 of P204 primary series) below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC62 for D614G [original strain], LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL). Analysis Set: P306 Part 2 PPIS-Neg and P204 PPIS-Neg was used for comparison of immune response. PPIS-Neg: all participants with negative Baseline SARS-CoV-2 status, who had baseline and P306 BD-Day 29/P204 Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint. n = participants evaluable for specified category.
    End point type
    Primary
    End point timeframe
    P306 BD-Day29/P204 Day 57
    End point values
    		 Part 2: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    312
    548
    Units: percentage of participants
        number (confidence interval 95%)
    100.0 (98.8 to 100.0)
    99.5 (98.4 to 99.9)
    Statistical analysis title
    		 Statistical Analysis 1
    Comparison groups
    Part 2: mRNA-1273.214 v P204 mRNA-1273 Primary Series
    Number of subjects included in analysis
    860
    Analysis specification
    Pre-specified
    Analysis type
    		 non-inferiority [10]
    Method
    		 Miettinen-Nurminen Score
    Parameter type
    		 SRR difference
    Point estimate
    0.5
    Confidence interval
         level
    		 95%
         sides
    2-sided
         lower limit
    		 -0.7
         upper limit
    		 1.6
    Notes
    [10] - Noninferiority: Lower bound of the 95% CI of the SRR difference >-10% with noninferiority margin of 10%

    Secondary: Part 1: SRR Against Omicron BA.1 and Ancestral SARS-CoV-2 (D614G) Strain After mRNA-1273.214 Compared with SRR After P204 mRNA-1273 primary Series in Same Age Group

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    End point title
    		 Part 1: SRR Against Omicron BA.1 and Ancestral SARS-CoV-2 (D614G) Strain After mRNA-1273.214 Compared with SRR After P204 mRNA-1273 primary Series in Same Age Group
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse relative to baseline (pre-Dose of primary series) SRR at a participant level was defined as a change from Baseline (pre-Dose 1 of P204 primary series) below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC122 for BA.1 [B.1.1.529], LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL and VAC62 for D614G [original strain], LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL). Analysis Set: P306 Part 1 PPIS and P204 PPIS was used for comparison of immune response. PPIS: all participants, regardless of Baseline SARS-CoV-2 status, who had baseline and P306 Day 57/P204 Day 57 Ab assessments, and met protocol-defined criteria for inclusion. "Number of subjects analyzed' = participants evaluable for this endpoint. n = participants evaluable for specified category.
    End point type
    Secondary
    End point timeframe
    P306 Day 57/P204 Day 57
    End point values
    		 Part 1: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    297
    602
    Units: percentage of participants
    number (confidence interval 95%)
        BA.1 (n= 293, 602)
    95.6 (92.5 to 97.6)
    85.7 (82.7 to 88.4)
        D614G (n= 297, 585)
    92.9 (89.4 to 95.6)
    99.5 (98.5 to 99.9)
    No statistical analyses for this end point

    Secondary: Part 1: nAb GMC Against Omicron BA.1 Compared with GMC of P204 mRNA-1273 2-dose Primary Series Against Ancestral (D614G) Strain in Participants of Same Age Group

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    End point title
    		 Part 1: nAb GMC Against Omicron BA.1 Compared with GMC of P204 mRNA-1273 2-dose Primary Series Against Ancestral (D614G) Strain in Participants of Same Age Group
    End point description
    Pseudovirus nAb measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC122 for BA.1 [B.1.1.529], LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL and VAC62 for D614G [original strain], LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL). Analysis Set: P306 Part 1 PPIS and P204 PPIS was used for comparison of immune response. PPIS: all participants, regardless of Baseline SARS-CoV-2 status, who had baseline and P306 Day 57/P204 Day 57 Ab assessments, and met protocol-defined criteria for inclusion. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 Day 57/P204 Day 57
    End point values
    		 Part 1: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    300
    594
    Units: AU/mL
        geometric mean (confidence interval 95%)
    3949.4 (3411.5 to 4572.0)
    1732.5 (1611.5 to 1862.5)
    No statistical analyses for this end point

    Secondary: Part 2: nAb GMC Against Omicron BA.1 Compared with GMC of P204 mRNA-1273 2-dose Primary Series Against Ancestral (D614G) Strain in Participants of Same Age Group

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    End point title
    		 Part 2: nAb GMC Against Omicron BA.1 Compared with GMC of P204 mRNA-1273 2-dose Primary Series Against Ancestral (D614G) Strain in Participants of Same Age Group
    End point description
    Pseudovirus nAb measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC122 for BA.1 [B.1.1.529], LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL and VAC62 for D614G [original strain], LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL. Analysis Set: P306 Part 2 PPIS-Neg and P204 PPIS-Neg was used for comparison of immune response. PPIS-Neg: all participants with negative Baseline SARS-CoV-2 status, who had baseline and P306 BD-Day 29/P204 Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 BD-Day 29/P204 Day 57
    End point values
    		 Part 2: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    316
    557
    Units: AU/mL
        geometric mean (confidence interval 95%)
    805.2 (730.0 to 888.2)
    1559.4 (1448.4 to 1679.0)
    No statistical analyses for this end point

    Secondary: Part 1: SRR Against Omicron BA.1 Compared with SRR of P204 mRNA-1273 2-dose Primary Series Against Ancestral (D614G) Strain in Participants of Same Age Group

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    End point title
    		 Part 1: SRR Against Omicron BA.1 Compared with SRR of P204 mRNA-1273 2-dose Primary Series Against Ancestral (D614G) Strain in Participants of Same Age Group
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse at a participant level was defined as a change from Baseline (pre-Dose 1 of P204 primary series) below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC122 for BA.1 [B.1.1.529], LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL and VAC62 for D614G [original strain], LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL). Analysis Set: P306 Part 1 PPIS and P204 PPIS was used for comparison of immune response. PPIS: all participants, regardless of Baseline SARS-CoV-2 status, who had baseline and P306 Day 57/P204 Day 57 Ab assessments, and met protocol-defined criteria for inclusion. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 Day 57/P204 Day 57
    End point values
    		 Part 1: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    293
    585
    Units: percentage of participants
        number (confidence interval 95%)
    95.6 (92.5 to 97.6)
    99.5 (98.5 to 99.9)
    No statistical analyses for this end point

    Secondary: Part 2: SRR Against Omicron BA.1 Compared with SRR of P204 mRNA-1273 2-dose Primary Series Against Ancestral (D614G) Strain in Participants of Same Age Group

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    End point title
    		 Part 2: SRR Against Omicron BA.1 Compared with SRR of P204 mRNA-1273 2-dose Primary Series Against Ancestral (D614G) Strain in Participants of Same Age Group
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse relative to baseline (pre-Dose of primary series) SRR at a participant level was defined as a change from Baseline (pre-Dose 1 of P204 primary series) below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC122 for BA.1 [B.1.1.529], LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL and VAC62 for D614G [original strain], LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL. Analysis Set: P306 Part 2 PPIS-Neg and P204 PPIS-Neg was used for comparison of immune response. PPIS-Neg: all participants with negative Baseline SARS-CoV-2 status, who had baseline and P306 BD-Day 29/P204 Day 57 Ab assessments, and met protocol-defined criteria for inclusion. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 BD-Day 29/P204 Day 57
    End point values
    		 Part 2: mRNA-1273.214 P204 mRNA-1273 Primary Series
    Number of subjects analysed
    312
    548
    Units: percentage of participation
        number (confidence interval 95%)
    99.0 (97.2 to 99.8)
    99.5 (98.4 to 99.9)
    No statistical analyses for this end point

    Secondary: Part 3: SRR Against Omicron XBB.1.5 After mRNA-1273.815 Administration

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    End point title
    		 Part 3: SRR Against Omicron XBB.1.5 After mRNA-1273.815 Administration
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse at a participant level was defined as a change from Baseline below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC150), LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL. Analysis Set: P306 Part 3 PPIS. PPIS: all participants, regardless of Baseline SARS-CoV-2 status, who had baseline and BD-Day 29 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    BD-Day 29
    End point values
    		 Part 3: mRNA-1273.815
    Number of subjects analysed
    274
    Units: percentage of participants
        number (confidence interval 95%)
    79.0 (73.4 to 83.8)
    No statistical analyses for this end point

    Secondary: Part 3: nAb GMC Against Omicron XBB.1.5 After mRNA-1273.815 Administration

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    End point title
    		 Part 3: nAb GMC Against Omicron XBB.1.5 After mRNA-1273.815 Administration
    End point description
    Pseudovirus nAb measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC150), LLOQ: 8 AU/mL, ULOQ: 24503 AU/mL. Analysis Set: P306 Part 3 PPIS. PPIS: all participants, regardless of Baseline SARS-CoV-2 status, who had baseline and BD-Day 29 Ab assessments, and met protocol-defined criteria for inclusion. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    BD-Day 29
    End point values
    		 Part 3: mRNA-1273.815
    Number of subjects analysed
    274
    Units: AU/mL
        geometric mean (confidence interval 95%)
    2827.4 (2389.9 to 3345.1)
    No statistical analyses for this end point

    Secondary: Part 4: SRR Against Omicron XBB.1.5 After mRNA-1273.815 Single Dose (Cohort A) Compared with SRR After 2 Doses of mRNA-1273.815 (Cohort B)

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    End point title
    		 Part 4: SRR Against Omicron XBB.1.5 After mRNA-1273.815 Single Dose (Cohort A) Compared with SRR After 2 Doses of mRNA-1273.815 (Cohort B)
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse at a participant level was defined as a change from Baseline below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC150 for XBB.1.5, LLOQ: 38 AU/mL, ULOQ: 6960 AU/mL). Analysis Set: P306 Part 4 Cohort A PPIS-Pos and P306 Part 4 Cohort B PPIS-Neg was used for comparison of immune response: PPIS-Pos: all participants who were SARS-CoV-2 positive at baseline who had baseline and P306 Cohort A Day 29 Ab assessments and had no major protocol deviations that impacted key or critical data. PPIS-Neg: all participants who were SARS-CoV-2 negative at baseline, who had baseline P306 Cohort B Day 57 Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 Cohort A Day 29/P306 Cohort B Day 57
    End point values
    		 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B
    Number of subjects analysed
    139
    76
    Units: percentage of participants
        number (confidence interval 95%)
    73.4 (65.2 to 80.5)
    96.1 (88.9 to 99.2)
    Statistical analysis title
    		 Statistical Analysis 1
    Comparison groups
    Part 4: mRNA-1273.815 Cohort A v Part 4: mRNA-1273.815 Cohort B
    Number of subjects included in analysis
    215
    Analysis specification
    Pre-specified
    Analysis type
    		 non-inferiority [11]
    Method
    		 Miettinen-Nurminen Score
    Parameter type
    		 SRR difference
    Point estimate
    -22.7
    Confidence interval
         level
    		 95%
         sides
    2-sided
         lower limit
    		 -31.3
         upper limit
    		 -13.5
    Notes
    [11] - Noninferiority criterion for SRR difference = lower bound of the 95% CI >-10%

    Secondary: Part 4: GMC Against Omicron XBB.1.5 After mRNA-1273.815 Single Dose (Cohort A) Compared with GMC After P204 mRNA-1273 2-dose Primary Series Against Ancestral SARS-CoV-2 (D614G) Strain

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    End point title
    		 Part 4: GMC Against Omicron XBB.1.5 After mRNA-1273.815 Single Dose (Cohort A) Compared with GMC After P204 mRNA-1273 2-dose Primary Series Against Ancestral SARS-CoV-2 (D614G) Strain
    End point description
    Pseudovirus nAb measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC150 for XBB.1.5 AU/mL, LLOQ: 38 AU/mL, ULOQ: 6960 AU/mL and VAC62 for D614G, LLOQ: 10, ULOQ: 111433 AU/mL). Analysis Set: P306 Part 4 Cohort A PPIS-Pos and P204 PPIS-Neg was used for comparison of immune response. PPIS-Pos: all participants with positive Baseline SARS-CoV-2 status, who had baseline and P306 Cohort A Day 29 Ab assessments, and met protocol-defined criteria for inclusion. PPIS-Neg: all participants with negative Baseline SARS-CoV-2 status, who had baseline and P204 Day 57 Ab assessments, and met protocol-defined criteria for inclusion. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 Cohort A Day 29/P204 Day 57
    End point values
    		 Part 4: mRNA-1273.815 Cohort A P204 mRNA-1273 Primary Series
    Number of subjects analysed
    143
    258
    Units: AU/mL
        geometric mean (confidence interval 95%)
    2074.1 (1722.5 to 2497.5)
    1439.1 (1253.3 to 1652.5)
    No statistical analyses for this end point

    Secondary: Part 4: SRR Against Omicron XBB.1.5 After mRNA-1273.815 Single Dose (Cohort A) Compared with SRR of P204 mRNA-1273 2-dose Primary Series Against Ancestral SARS-CoV-2 (D614G) Strain

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    End point title
    		 Part 4: SRR Against Omicron XBB.1.5 After mRNA-1273.815 Single Dose (Cohort A) Compared with SRR of P204 mRNA-1273 2-dose Primary Series Against Ancestral SARS-CoV-2 (D614G) Strain
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse at a participant level was defined as a change from Baseline below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC150 for XBB.1.5 AU/mL, LLOQ: 38 AU/mL, ULOQ: 6960 AU/mL and VAC62 for D614G, LLOQ: 10 AU/mL, ULOQ: 111433 AU/mL). Analysis Set: P306 Part 4 PPIS-Pos and P204 PPIS-Neg was used for comparison of immune response. PPIS-Pos: all participants with positive Baseline SARS-CoV-2 status, who had baseline and P306 Cohort A Day 29 Ab assessments, and met protocol-defined criteria for inclusion. PPIS-Neg: all participants with negative Baseline SARS-CoV-2 status, who had baseline and P204 Day 57 Ab assessments, and met protocol-defined criteria for inclusion. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 Cohort A Day 29/P204 Day 57
    End point values
    		 Part 4: mRNA-1273.815 Cohort A P204 mRNA-1273 Primary Series
    Number of subjects analysed
    139
    253
    Units: percentage of participants
        number (confidence interval 95%)
    73.4 (65.2 to 80.5)
    99.2 (97.2 to 99.9)
    No statistical analyses for this end point

    Secondary: Part 4: GMC Against Omicron XBB.1.5 After mRNA-1273.815 Single Dose (Cohort A) Compared with GMC After 2 Doses of mRNA-1273.815 (Cohort B), Regardless of Prior Infection

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    End point title
    		 Part 4: GMC Against Omicron XBB.1.5 After mRNA-1273.815 Single Dose (Cohort A) Compared with GMC After 2 Doses of mRNA-1273.815 (Cohort B), Regardless of Prior Infection
    End point description
    Pseudovirus nAb measured using PsVNA assay. Antibody values reported <LLOQ replaced by 0.5*LLOQ. Values >ULOQ replaced by ULOQ if actual values not available. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC150 for XBB.1.5, LLOQ: 38 AU/mL, ULOQ: 6960 AU/mL). Analysis Set: P306 Part 4 Cohort A PPIS-Pos and P306 Part 4 Cohort B PPIS-Neg was used for comparison of immune response. PPIS-Pos: all participants who were SARS-CoV-2 positive at baseline who had baseline and P306 Day 29 Cohort A Ab assessments and had no major protocol deviations that impacted key or critical data. PPIS-Neg: all participants who were SARS-CoV-2 negative at baseline, who had baseline P306 Day 57 Cohort B Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 Day 29 Cohort A/P306 Day 57 Cohort B
    End point values
    		 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B
    Number of subjects analysed
    148
    352
    Units: AU/mL
        geometric mean (confidence interval 95%)
    1975.5 (1593.2 to 2449.6)
    3768.9 (3278.2 to 4333.0)
    No statistical analyses for this end point

    Secondary: Part 4: SRR against Omicron XBB.1.5 after mRNA-1273.815 Single Dose (Cohort A) Compared with SRR After 2 Doses of mRNA-1273.815 (Cohort B), Regardless of Prior Infection

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    End point title
    		 Part 4: SRR against Omicron XBB.1.5 after mRNA-1273.815 Single Dose (Cohort A) Compared with SRR After 2 Doses of mRNA-1273.815 (Cohort B), Regardless of Prior Infection
    End point description
    Percentage of participants with seroresponse for pseudovirus nAb measured using PsVNA assay are reported. Seroresponse at a participant level was defined as a change from Baseline below the LLOQ to ≥4*LLOQ, or at least a 4-fold rise if Baseline was ≥ the LLOQ. Serum nAb level against SARS-CoV-2 were measured by pseudotyped virus neutralization (VAC150 for XBB.1.5, LLOQ: 38 AU/mL, ULOQ: 6960 AU/mL). Analysis Set: P306 Part 4 Cohort A PPIS-Pos and P306 Part 4 Cohort B PPIS-Neg was used for comparison of immune response. PPIS-Pos: all participants who were SARS-CoV-2 positive at baseline who had baseline and P306 Day 29 Cohort A Ab assessments and had no major protocol deviations that impacted key or critical data. PPIS-Neg: all participants who were SARS-CoV-2 negative at baseline, who had baseline P306 Day 57 Cohort B Ab assessments, and had no major protocol deviations that impacted key or critical data. "Number of subjects analyzed' = participants evaluable for this endpoint.
    End point type
    Secondary
    End point timeframe
    P306 Day 29 Cohort A/P306 Day 57 Cohort B
    End point values
    		 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B
    Number of subjects analysed
    144
    347
    Units: percentage of participants
        number (confidence interval 95%)
    73.6 (65.6 to 80.6)
    89.0 (85.3 to 92.1)
    No statistical analyses for this end point

    Adverse events

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    Adverse events information
    Timeframe for reporting adverse events
    Up to Day 394
    Adverse event reporting additional description
    Safety Set: received at least 1 dose of study drug.. Active surveillance for COVID-19 was included in Parts 1 and 2, but not in Parts 3 and 4, so COVID-19/SARS-CoV-2 infections were considered clinical events and not AEs in Parts 1 and 2, and considered as AEs in Parts and Part 4.
    Assessment type
    		 Systematic
    Dictionary used for adverse event reporting
    Dictionary name
    		 MedDRA
    Dictionary version
    23.0
    Reporting groups
    Reporting group title
    Part 2: mRNA-1273.214
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had previously been vaccinated with a mRNA-1273 primary series, received a single IM 10 µg BD of mRNA-1273.214 vaccine at least 4 months after completion of the mRNA-1273 primary series.

    Reporting group title
    Part 1: mRNA-1273.214
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injections of mRNA-1273.214 vaccine as a 2-dose series on Day 1 and Day 29.

    Reporting group title
    Part 4: mRNA-1273.815 Cohort A
    Reporting group description
    		 Participants, 2 to <5 years of age, who had not been previously vaccinated against SARS-CoV-2, received a single 25 μg IM injection of mRNA-1273.815 vaccine on Day 1.

    Reporting group title
    Part 4: mRNA-1273.815 Cohort B
    Reporting group description
    		 Participants, 6 months to <2 years of age, who had not been previously vaccinated against SARS-CoV-2, received 25 μg IM injections of mRNA-1273.815 vaccine as a 2-dose series on Day 1 and Day 29.

    Reporting group title
    Part 3: mRNA-1273.815
    Reporting group description
    		 Participants, 6 months to <6 years of age, who had previously been vaccinated with an authorized/approved COVID-19 vaccine, received a single IM 25 μg BD of mRNA-1273.815 vaccine on BD Day 1, at least 4 months after the last dose of a COVID-19 vaccine.

    Serious adverse events
    		 Part 2: mRNA-1273.214 Part 1: mRNA-1273.214 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B Part 3: mRNA-1273.815
    Total subjects affected by serious adverse events
         subjects affected / exposed
    9 / 539 (1.67%)
    10 / 391 (2.56%)
    0 / 199 (0.00%)
    13 / 399 (3.26%)
    5 / 274 (1.82%)
         number of deaths (all causes)
    0
    0
    0
    0
    0
         number of deaths resulting from adverse events
    0
    0
    0
    0
    0
    Investigations
    Cardiac murmur
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Congenital, familial and genetic disorders
    Aberrant aortic arch
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Cardiac disorders
    Left ventricular hypertrophy
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Nervous system disorders
    Febrile convulsion
         subjects affected / exposed
    1 / 539 (0.19%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    1 / 274 (0.36%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
    0 / 0
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Cerebellar ataxia
         subjects affected / exposed
    1 / 539 (0.19%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Seizure
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    1 / 399 (0.25%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Status epilepticus
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    1 / 274 (0.36%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Blood and lymphatic system disorders
    Anaemia
         subjects affected / exposed
    0 / 539 (0.00%)
    2 / 391 (0.51%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 3
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Immune system disorders
    Anaphylactic reaction
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Ear and labyrinth disorders
    Hypoacusis
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Gastrointestinal disorders
    Vomiting
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Respiratory, thoracic and mediastinal disorders
    Asthma
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 2
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Adenoidal hypertrophy
         subjects affected / exposed
    1 / 539 (0.19%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Bronchial obstruction
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    1 / 399 (0.25%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Infections and infestations
    Pneumonia
         subjects affected / exposed
    1 / 539 (0.19%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    5 / 399 (1.25%)
    1 / 274 (0.36%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 1
    0 / 0
    0 / 5
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Bronchiolitis
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    3 / 399 (0.75%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 3
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Pneumonia respiratory syncytial viral
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    3 / 399 (0.75%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 3
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Respiratory syncytial virus infection
         subjects affected / exposed
    1 / 539 (0.19%)
    2 / 391 (0.51%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 2
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Respiratory syncytial virus bronchiolitis
         subjects affected / exposed
    2 / 539 (0.37%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 2
    0 / 0
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Bronchitis
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    1 / 399 (0.25%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Gastroenteritis clostridial
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    1 / 399 (0.25%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Herpangina
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    1 / 399 (0.25%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Lower respiratory tract infection
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    1 / 274 (0.36%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Otitis media
         subjects affected / exposed
    1 / 539 (0.19%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Respiratory tract infection
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    1 / 274 (0.36%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Parainfluenzae virus infection
         subjects affected / exposed
    1 / 539 (0.19%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Urinary tract infection
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    1 / 274 (0.36%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Tooth infection
         subjects affected / exposed
    0 / 539 (0.00%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    1 / 274 (0.36%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Staphylococcal scalded skin syndrome
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Metabolism and nutrition disorders
    Hypoglycaemia
         subjects affected / exposed
    0 / 539 (0.00%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Dehydration
         subjects affected / exposed
    1 / 539 (0.19%)
    1 / 391 (0.26%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 2
    0 / 0
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    0 / 0
    Frequency threshold for reporting non-serious adverse events: 5%
    Non-serious adverse events
    		 Part 2: mRNA-1273.214 Part 1: mRNA-1273.214 Part 4: mRNA-1273.815 Cohort A Part 4: mRNA-1273.815 Cohort B Part 3: mRNA-1273.815
    Total subjects affected by non serious adverse events
         subjects affected / exposed
    245 / 539 (45.45%)
    178 / 391 (45.52%)
    37 / 199 (18.59%)
    161 / 399 (40.35%)
    48 / 274 (17.52%)
    Infections and infestations
    Nasopharyngitis
         subjects affected / exposed
    18 / 539 (3.34%)
    10 / 391 (2.56%)
    31 / 199 (15.58%)
    117 / 399 (29.32%)
    20 / 274 (7.30%)
         occurrences all number
    22
    12
    33
    148
    26
    Gastroenteritis viral
         subjects affected / exposed
    9 / 539 (1.67%)
    22 / 391 (5.63%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    4 / 274 (1.46%)
         occurrences all number
    9
    23
    0
    0
    4
    Otitis media acute
         subjects affected / exposed
    34 / 539 (6.31%)
    24 / 391 (6.14%)
    0 / 199 (0.00%)
    4 / 399 (1.00%)
    6 / 274 (2.19%)
         occurrences all number
    44
    52
    0
    4
    6
    Otitis media
         subjects affected / exposed
    71 / 539 (13.17%)
    55 / 391 (14.07%)
    1 / 199 (0.50%)
    7 / 399 (1.75%)
    2 / 274 (0.73%)
         occurrences all number
    99
    89
    1
    7
    2
    Pharyngitis streptococcal
         subjects affected / exposed
    33 / 539 (6.12%)
    38 / 391 (9.72%)
    1 / 199 (0.50%)
    0 / 399 (0.00%)
    2 / 274 (0.73%)
         occurrences all number
    40
    50
    1
    0
    2
    Respiratory syncytial virus infection
         subjects affected / exposed
    27 / 539 (5.01%)
    11 / 391 (2.81%)
    0 / 199 (0.00%)
    0 / 399 (0.00%)
    0 / 274 (0.00%)
         occurrences all number
    28
    11
    0
    0
    0
    Respiratory tract infection
         subjects affected / exposed
    1 / 539 (0.19%)
    0 / 391 (0.00%)
    0 / 199 (0.00%)
    23 / 399 (5.76%)
    0 / 274 (0.00%)
         occurrences all number
    1
    0
    0
    30
    0
    Upper respiratory tract infection
         subjects affected / exposed
    119 / 539 (22.08%)
    84 / 391 (21.48%)
    4 / 199 (2.01%)
    16 / 399 (4.01%)
    18 / 274 (6.57%)
         occurrences all number
    179
    168
    4
    16
    21
    Viral upper respiratory tract infection
         subjects affected / exposed
    20 / 539 (3.71%)
    38 / 391 (9.72%)
    1 / 199 (0.50%)
    1 / 399 (0.25%)
    1 / 274 (0.36%)
         occurrences all number
    22
    47
    1
    1
    1

    More information

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    Substantial protocol amendments (globally)
    Were there any global substantial amendments to the protocol? Yes
    Date
    Amendment
    08 Dec 2022
    Updated the coprimary endpoints for Part 1 and Part 2
    28 Nov 2023
    Added Parts 3 and 4 (mRNA- 1273.815) to the study
    17 Jan 2024
    - Updated study endpoints - Updated immunogenicity and vaccine effective assessments - Additional statistical analysis added

    Interruptions (globally)
    Were there any global interruptions to the trial? No

    Limitations and caveats
    Limitations of the trial such as small numbers of subjects analysed or technical problems leading to unreliable data.
    None reported
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