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;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;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;Parts 1, 2, and 3: Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs);Parts 1, 2, and 3: Number of Participants With Unsolicited AEs;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;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;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;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;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;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

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;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;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;Parts 1, 2, and 3: Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs);Parts 1, 2, and 3: Number of Participants With Unsolicited AEs;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;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;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;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;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;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

Geometric Mean (GM) Value of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Specific Serum Antibody;GM Value of Post-Booster Dose SARS-CoV-2 Specific Serum Antibody;Number of Participants with Adverse Events of Special Interest (AESIs), Including Multisystem Inflammatory Syndrome in Children (MIS-C), Myocarditis and/or Pericarditis;Number of Participants with AEs Leading to Discontinuation From Study Post-Booster Dose Through the Last Day of Study Participation;Number of Participants with Medically-Attended AEs (MAAEs);Number of Participants with Serious Adverse Events (SAEs);Number of Participants with Serum Antibody Levels that Meet or Exceed the Threshold of Protection From COVID-19;Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants with Unsolicited Adverse Events (AEs);Seroresponse Rate of Post-Booster Dose of Vaccine Recipients;Seroresponse Rate of Vaccine Recipients

Geometric Mean (GM) Value of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Specific Serum Antibody;GM Value of Post-Booster Dose SARS-CoV-2 Specific Serum Antibody;Number of Participants with Adverse Events of Special Interest (AESIs), Including Multisystem Inflammatory Syndrome in Children (MIS-C), Myocarditis and/or Pericarditis;Number of Participants with AEs Leading to Discontinuation From Study Post-Booster Dose Through the Last Day of Study Participation;Number of Participants with Medically-Attended AEs (MAAEs);Number of Participants with Serious Adverse Events (SAEs);Number of Participants with Serum Antibody Levels that Meet or Exceed the Threshold of Protection From COVID-19;Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants with Unsolicited Adverse Events (AEs);Seroresponse Rate of Post-Booster Dose of Vaccine Recipients;Seroresponse Rate of Vaccine Recipients

Geometric Mean (GM) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Specific Serum Antibody;Number of Participants with Adverse Events of Special Interest (AESIs), Including Multisystem Inflammatory Syndrome in Children (MIS-C), Myocarditis and/or Pericarditis;Number of Participants with Medically-Attended AEs (MAAEs);Number of Participants with Serious Adverse Events (SAEs);Number of Participants with Serum Antibody Levels that Meet or Exceed the Threshold of Protection From COVID-19;Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants with Unsolicited Adverse Events (AEs);Seroresponse Rate of Vaccine Recipients

Geometric Mean (GM) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Specific Serum Antibody;Number of Participants with Adverse Events of Special Interest (AESIs), Including Multisystem Inflammatory Syndrome in Children (MIS-C), Myocarditis and/or Pericarditis;Number of Participants with Medically-Attended AEs (MAAEs);Number of Participants with Serious Adverse Events (SAEs);Number of Participants with Serum Antibody Levels that Meet or Exceed the Threshold of Protection From COVID-19;Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants with Unsolicited Adverse Events (AEs);Seroresponse Rate of Vaccine Recipients

Geometric Mean (GM) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Specific Serum Antibody;Number of Participants with Adverse Events of Special Interest (AESIs), Including Multisystem Inflammatory Syndrome in Children (MIS-C);Number of Participants with Medically-Attended AEs (MAAEs);Number of Participants with Serious Adverse Events (SAEs);Number of Participants with Serum Antibody Levels that Meet or Exceed the Threshold of Protection From COVID-19;Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants with Unsolicited Adverse Events (AEs);Seroresponse Rate of Vaccine Recipients

Geometric Mean (GM) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Specific Serum Antibody;Number of Participants with Adverse Events of Special Interest (AESIs), Including Multisystem Inflammatory Syndrome in Children (MIS-C);Number of Participants with Medically-Attended AEs (MAAEs);Number of Participants with Serious Adverse Events (SAEs);Number of Participants with Serum Antibody Levels that Meet or Exceed the Threshold of Protection From COVID-19;Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants with Unsolicited Adverse Events (AEs);Seroresponse Rate of Vaccine Recipients

Geometric Mean (GM) of SARS-CoV-2 Specific Neutralizing Antibody (nAb);Number of Participants with Adverse Events of Special Interest (AESIs), including Multisystem Inflammatory Syndrome in Children (MIS-C);Number of Participants with Medically-Attended AEs (MAAEs);Number of Participants with Serious Adverse Events (SAEs);Number of Participants with Serum Antibody (Ab) Levels that Meet or Exceed the Threshold of Protection from COVID-19;Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants with Unsolicited Adverse Events (AEs);Seroresponse Rate of Vaccine Recipients

Geometric Mean (GM) of SARS-CoV-2 Specific Neutralizing Antibody (nAb);Number of Participants with Adverse Events of Special Interest (AESIs), including Multisystem Inflammatory Syndrome in Children (MIS-C);Number of Participants with Medically-Attended AEs (MAAEs);Number of Participants with Serious Adverse Events (SAEs);Number of Participants with Serum Antibody (Ab) Levels that Meet or Exceed the Threshold of Protection from COVID-19;Number of Participants with Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants with Unsolicited Adverse Events (AEs);Seroresponse Rate of Vaccine Recipients