Groups 1, 2, 3, 4, 5 and 6: Number of Participants With MAAEs 6 Months Post-Dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Solicited Local Adverse Events (AEs) at 7 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Solicited Local Adverse Events (AEs) at 7 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Solicited Systemic AEs at 7 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Solicited Systemic AEs at 7 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Unsolicited AEs at 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Unsolicited AEs at 28 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by S-ELISA at 14 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by Spike-enzyme-linked Immunosorbent Assay (S-ELISA) at 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Groups 1, 2, 3, 4, and 5: Number of Participants With Medically-attended Adverse Events (MAAEs) 6 Months Post-Dose 1;Groups 1, 2, and 3: Number of Participants With Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Groups 1, 2, and 3: Number of Participants With MAAEs Leading to Discontinuation;Groups 1, 2, and 3: Number of Participants With Serious Adverse Events (SAEs);Groups 4, 5 and 6: Number of Participants With AESI (Including MIS-C);Groups 4, 5 and 6: Number of Participants With MAAEs Leading to Discontinuation;Groups 4, 5 and 6: Number of Participants With Serious Adverse Events (SAEs);Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

Groups 1, 2, 3, 4, 5 and 6: Number of Participants With MAAEs 6 Months Post-Dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Solicited Local Adverse Events (AEs) at 7 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Solicited Local Adverse Events (AEs) at 7 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Solicited Systemic AEs at 7 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Solicited Systemic AEs at 7 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Unsolicited AEs at 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants With Unsolicited AEs at 28 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by S-ELISA at 14 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by Spike-enzyme-linked Immunosorbent Assay (S-ELISA) at 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Groups 1, 2, 3, 4, and 5: Number of Participants With Medically-attended Adverse Events (MAAEs) 6 Months Post-Dose 1;Groups 1, 2, and 3: Number of Participants With Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Groups 1, 2, and 3: Number of Participants With MAAEs Leading to Discontinuation;Groups 1, 2, and 3: Number of Participants With Serious Adverse Events (SAEs);Groups 4, 5 and 6: Number of Participants With AESI (Including MIS-C);Groups 4, 5 and 6: Number of Participants With MAAEs Leading to Discontinuation;Groups 4, 5 and 6: Number of Participants With Serious Adverse Events (SAEs);Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

Groups 1, 2, 3, 4, 5 and 6: Number of Participants with MAAEs;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Medically-attended Adverse Events (MAAEs);Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by Spike-enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2;Groups 1, 2 and 3: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Groups 1, 2 and 3: Number of Participants with MAAEs Leading to Discontinuation;Groups 1, 2 and 3: Number of Participants with Serious Adverse Events (SAEs);Groups 4, 5 and 6: Number of Participants with AESI (Including MIS-C);Groups 4, 5 and 6: Number of Participants with MAAEs Leading to Discontinuation;Groups 4, 5 and 6: Number of Participants with SAEs

Groups 1, 2, 3, 4, 5 and 6: Number of Participants with MAAEs;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Medically-attended Adverse Events (MAAEs);Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by Spike-enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Groups 1, 2, 3, 4, 5 and 6: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2;Groups 1, 2 and 3: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Groups 1, 2 and 3: Number of Participants with MAAEs Leading to Discontinuation;Groups 1, 2 and 3: Number of Participants with Serious Adverse Events (SAEs);Groups 4, 5 and 6: Number of Participants with AESI (Including MIS-C);Groups 4, 5 and 6: Number of Participants with MAAEs Leading to Discontinuation;Groups 4, 5 and 6: Number of Participants with SAEs

Part 1: Groups 1-3: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Part 1: Groups 1-3: Number of Participants with MAAEs Leading to Discontinuation;Part 1: Groups 1-3: Number of Participants with Serious Adverse Events (SAEs);Part 1: Groups 4-6: Number of Participants with AESI (Including MIS-C);Part 1: Groups 4-6: Number of Participants with MAAEs Leading to Discontinuation;Part 1: Groups 4-6: Number of Participants with SAEs;Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents;Part 2: Number of Participants with AESI (Including MIS-C);Part 2: Number of Participants with MAAEs Leading to Discontinuation;Part 2: Number of Participants with SAEs;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Parts 1 and 2: Number of Participants with MAAEs;Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs);Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

Part 1: Groups 1-3: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Part 1: Groups 1-3: Number of Participants with MAAEs Leading to Discontinuation;Part 1: Groups 1-3: Number of Participants with Serious Adverse Events (SAEs);Part 1: Groups 4-6: Number of Participants with AESI (Including MIS-C);Part 1: Groups 4-6: Number of Participants with MAAEs Leading to Discontinuation;Part 1: Groups 4-6: Number of Participants with SAEs;Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents;Part 2: Number of Participants with AESI (Including MIS-C);Part 2: Number of Participants with MAAEs Leading to Discontinuation;Part 2: Number of Participants with SAEs;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Parts 1 and 2: Number of Participants with MAAEs;Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs);Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

None

Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1 [ Time Frame: 7 days post-dose 1 (Day 8) ] An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Solicited local AEs are pre-defined local (at the injection site) AEs for which participants are specifically asked and which are noted by participants in their reactogenicity diary for 7 days post each vaccination. Solicited local AEs are: injection site pain/tenderness, erythema, swelling at the vaccination site. Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2 [ Time Frame: 7 days post-dose 2 (Day 64) ] An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Solicited local AEs are pre-defined local (at the injection site) AEs for which participants are specifically asked and which are noted by participants in their reactogenicity diary for 7 days post each vaccination. Solicited local AEs are: injection site pain/tenderness, erythema, swelling at the vaccination site. Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1 [ Time Frame: 7 days post-dose 1 (Day 8) ] Participants will be instructed on how to note signs and symptoms in the diary on a daily basis for 7 days post-vaccination (day of vaccination and the subsequent 7 days) for the following solicited systemic AEs: fatigue, headache, nausea, and myalgia. Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2 [ Time Frame: 7 days post-dose 2 (Day 64) ] Participants will be instructed on how to note signs and symptoms in the diary on a daily basis for 7 days post-vaccination (Day of vaccination and the subsequent 7 days) for following solicited systemic AEs: fatigue, headache, nausea, and myalgia. Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1 [ Time Frame: 28 days post-dose 1 (Day 29) ] Unsolicited AEs are all AEs for which the participant is not specifically questioned in the participant's reactogenicity diary. Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2 [ Time Frame: 28 days post-dose 2 (Day 85) ] Unsolicited AEs are all AEs for which the participant is not specifically questioned in the participant's reactogenicity diary. Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs) [ Time Frame: From the first vaccination until 6 months post-dose 1 (Up to Day 184) ] MAAEs are defined as AEs with medically-attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits will not be considered medically-attended visits. New onset of chronic diseases will be collected as part of the MAAEs. Parts 1 and 2: Number of Participants with MAAEs [ Time Frame: From the first vaccination until 6 months post-dose 2 (Up to Day 240) ] MAAEs are defined as AEs with medically-attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits will not be considered medically-attended visits. New onset of chronic diseases will be collected as part of the MAAEs. Part 1: Groups 1-3: Number of Participants with MAAEs Leading to Discontinuation [ Time Frame: Up to Day 550 (12 months after booster vaccination on Day 184) ] MAAEs are defined as AEs with medically-attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits will not be considered medically-attended visits. New onset of chronic diseases will be collected as part of the MAAEs. Part 1: Groups 4-6: Number of Participants with MAAEs Leading to Discontinuation [ Time Frame: Up to Day 789 (12 months after booster vaccination on Day 423) ] MAAEs are defined as AEs with medically-attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits will not be considered medically-attended visits. New onset of chronic diseases will be collected as part of the MAAEs. Part 2: Number of Participants with MAAEs Leading to Discontinuation [ Time Frame: Until completion of the participant's last study related procedure (Up to Day 420) ] MAAEs are defined as AEs with medically-attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits will not be considered medically-attended visits. New onset of chronic diseases will be collected as part of the MAAEs. Part 1: Groups 1-3: Number of Participants with Serious Adverse Events (SAEs) [ Time Frame: Up to Day 550 (12 months after booster vaccination on Day 184) ] SAE is any untoward medical occurrence that at any dose results in any of the following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important. Part 1: Groups 4-6: Number of Participants with SAEs [ Time Frame: Up to Day 789 (12 months after booster vaccination on Day 423) ] SAE is any untoward medical occurrence that at any dose results in any of the following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important. Part 2: Number of Participants with SAEs [ Time Frame: Up to Day 420 ] SAE is any untoward medical occurrence that at any dose results in any of the following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important. Part 1: Groups 1-3: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]) [ Time Frame: Up to Day 550 (12 months after booster vaccination on Day 184) ] Number of participants with AESI (including MIS-C) will be reported. Thrombosis with thrombocytopenia syndrome (TTS) and MIS-C are considered to be AESIs. Part 1: Groups 4-6: Number of Participants with AESI (Including MIS-C) [ Time Frame: Up to Day 789 (12 months after booster vaccination on Day 423) ] Number of participants with AESI (including MIS-C) will be reported. Thrombosis with TTS and MIS-C are considered to be AESIs. Part 2: Number of Participants with AESI (Including MIS-C) [ Time Frame: Up to Day 420 ] Number of participants with AESI (including MIS-C) will be reported. Thrombosis with TTS and MIS-C are considered to be AESIs. Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1 [ Time Frame: 28 days post-dose 1 (Day 29) ] Serological response to vaccination will be measured by S-ELISA (ELISA Units/mL [EU/mL]) or equivalent assay 28 days post-dose 1. Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2 [ Time Frame: 14 days post-dose 2 (Day 71) ] Serological response to vaccination will be measured by S-ELISA (ELISA Units/mL [EU/mL]) or equivalent assay 14 days post-dose 2. Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1 [ Time Frame: 28 days post-dose 1 (Day 29) ] Serological response to vaccination will be measured by VNA titers 28 days post-dose 1. Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2 [ Time Frame: 14 days post-dose 2 (Day 71) ] Serological response to vaccination will be measured by VNA titers 14 days post-dose 2. Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents [ Time Frame: 28 days post-dose 1 (Day 29) ] Non-inferiority (NI) will be assessed in terms of humoral immune response expressed by the GMT of VNA 28 days post-dose 1 in adolescents. Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents [ Time Frame: 28 days after first vaccination (Day 29) ] NI will be assessed in terms of humoral immune response expressed by the seroresponse rate of the VNA 28 days after first vaccination in adolescents. Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents [ Time Frame: 28 days post-dose 1 (Day 29) ] NI will be assessed in terms of humoral immune response expressed by the GMT of VNA, 28 days post-dose 1 in adolescents. Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents [ Time Frame: 14 days post-dose 2 (Day 71) ] Serological response to vaccination will be measured by the GMT of VNA, 14 days post-dose 2 in adolescents. Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents [ Time Frame: 14 days post-dose 2 (Day 71) ] NI will be assessed in terms of humoral immune response expressed by the seroresponse rate of the VNA 14 days post-dose 2 in adolescents. Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents [ Time Frame: 14 days post-dose 2 (Day 71) ] NI will be assessed in terms of humoral immune response expressed by the GMT of VNA 14 days post-dose 2 in adolescents.

Part 1: Groups 1-3: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Part 1: Groups 1-3: Number of Participants with MAAEs Leading to Discontinuation;Part 1: Groups 1-3: Number of Participants with Serious Adverse Events (SAEs);Part 1: Groups 4-6: Number of Participants with AESI (Including MIS-C);Part 1: Groups 4-6: Number of Participants with MAAEs Leading to Discontinuation;Part 1: Groups 4-6: Number of Participants with SAEs;Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents;Part 2: Number of Participants with AESI (Including MIS-C);Part 2: Number of Participants with MAAEs Leading to Discontinuation;Part 2: Number of Participants with SAEs;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Parts 1 and 2: Number of Participants with MAAEs;Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs);Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

Part 1: Groups 1-3: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Part 1: Groups 1-3: Number of Participants with MAAEs Leading to Discontinuation;Part 1: Groups 1-3: Number of Participants with Serious Adverse Events (SAEs);Part 1: Groups 4-6: Number of Participants with AESI (Including MIS-C);Part 1: Groups 4-6: Number of Participants with MAAEs Leading to Discontinuation;Part 1: Groups 4-6: Number of Participants with SAEs;Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents;Part 2: Number of Participants with AESI (Including MIS-C);Part 2: Number of Participants with MAAEs Leading to Discontinuation;Part 2: Number of Participants with SAEs;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Parts 1 and 2: Number of Participants with MAAEs;Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs);Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Seroresponse Rate of VNA to 14 Days Post-dose 2;Part 2: Seroresponse Rate of VNA to 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Parts 1 and 2: Number of Participants with MAAEs;Parts 1 and 2: Number of Participants with MAAEs Leading to Discontinuation;Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs);Parts 1 and 2: Number of Participants with Serious Adverse Events (SAEs);Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Seroresponse Rate of VNA to 14 Days Post-dose 2;Part 2: Seroresponse Rate of VNA to 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Parts 1 and 2: Number of Participants with MAAEs;Parts 1 and 2: Number of Participants with MAAEs Leading to Discontinuation;Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs);Parts 1 and 2: Number of Participants with Serious Adverse Events (SAEs);Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Part 2: Change from Baseline in Seroresponse Rate of VNA to 14 Days Post-dose 2;Part 2: Change from Baseline in Seroresponse Rate of VNA to 28 Days Post-dose 1;Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents and Young Adults;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents and Young Adults;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Young Adults;Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents and Young Adults;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Young Adults;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents and Young adults;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days Post-dose 1 in Young Adults;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 28 Days Post-dose 1 in Young Adults;Parts 1 and 2: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Parts 1 and 2: Number of Participants with MAAEs;Parts 1 and 2: Number of Participants with MAAEs Leading to Discontinuation;Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs);Parts 1 and 2: Number of Participants with Serious Adverse Events (SAEs);Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2

Part 1: Serological Response to Vaccination Measured by Enzyme-linked Immunosorbent Assay (S-ELISA) or Equivalent Assay 28 Days Post-dose 1;Part 1: Serological Response to Vaccination Measured by S-ELISA or Equivalent Assay 14 Days Post-dose 2;Part 2: Change from Baseline in Seroresponse Rate of VNA to 14 Days Post-dose 2;Part 2: Change from Baseline in Seroresponse Rate of VNA to 28 Days Post-dose 1;Part 2: Humoral Immune Response Expressed by the Geometric Mean Titer (GMT) of VNA 28 Days Post-dose 1 in Adolescents and Young Adults;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Adolescents and Young Adults;Part 2: Humoral Immune Response Expressed by the GMT of VNA 14 Days Post-dose 2 in Young Adults;Part 2: Humoral Immune Response Expressed by the GMT of VNA 28 Days Post-dose 1 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Adolescents and Young Adults;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 14 Days Post-dose 2 in Young Adults;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days after First Vaccination in Adolescents and Young adults;Part 2: Humoral Immune Response Expressed by the Seroresponse Rate of the VNA 28 Days Post-dose 1 in Young Adults;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 14 Days Post-dose 2 in Adolescents;Part 2: Serological Response to Vaccination as Measured by the GMT of VNA 28 Days Post-dose 1 in Young Adults;Parts 1 and 2: Number of Participants with Adverse Events of Special Interest (AESI) (Including Multisystem Inflammatory Syndrome in Children [MIS-C]);Parts 1 and 2: Number of Participants with MAAEs;Parts 1 and 2: Number of Participants with MAAEs Leading to Discontinuation;Parts 1 and 2: Number of Participants with Medically-attended Adverse Events (MAAEs);Parts 1 and 2: Number of Participants with Serious Adverse Events (SAEs);Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Local Adverse Events (AEs) 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 1;Parts 1 and 2: Number of Participants with Solicited Systemic AEs 7 Days Post-dose 2;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 1;Parts 1 and 2: Number of Participants with Unsolicited AEs 28 Days Post-dose 2;Parts 1 and 2: Serological Response to Vaccination Measured by Virus Neutralization Assay (VNA) Titers 28 Days Post-dose 1;Parts 1 and 2: Serological Response to Vaccination Measured by VNA Titers 14 Days Post-dose 2