Part 2: Change From Baseline in Geometric Mean Titer (GMT) of Antibodies for Influenza at Day 29, as Measured by Hemagglutination Inhibition (HAI) Assay;Part 2: Change From Baseline in GMT of Antibodies for SARS-CoV-2 at Day 29, as Measured by Pseudovirus Neutralization Assay (PsVNA);Part 2: Geometric Mean Fold-Rise (GMFR) of Antibodies for Influenza at Day 29 Compared to Baseline (Day 1), as Measured by HAI Assay;Part 2: GMFR of Antibodies for SARS-CoV-2 at Day 29 Compared to Baseline (Day 1), as Measured by PsVNA;Part 2: Influenza: Percentage of Participants with Seroconversion at Day 29, as Measured by HAI Assay;Part 2: SARS-CoV-2: Percentage of Participants with Seroresponse at Day 29, as Measured by PsVNA;Parts 1 and 2: Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs);Parts 1 and 2: Number of Participants With Unsolicited Adverse Events (AEs) and Severe AEs;Parts 1 and 2: Number of Participants With Unsolicited Medically Attended Adverse Events (MAAEs), Adverse Events of Special Interest (AESIs), Serious Adverse Events (SAEs), and AEs Leading to Discontinuation of Study

Part 2: Change From Baseline in Geometric Mean Titer (GMT) of Antibodies for Influenza at Day 29, as Measured by Hemagglutination Inhibition (HAI) Assay;Part 2: Change From Baseline in GMT of Antibodies for SARS-CoV-2 at Day 29, as Measured by Pseudovirus Neutralization Assay (PsVNA);Part 2: Geometric Mean Fold-Rise (GMFR) of Antibodies for Influenza at Day 29 Compared to Baseline (Day 1), as Measured by HAI Assay;Part 2: GMFR of Antibodies for SARS-CoV-2 at Day 29 Compared to Baseline (Day 1), as Measured by PsVNA;Part 2: Influenza: Percentage of Participants with Seroconversion at Day 29, as Measured by HAI Assay;Part 2: SARS-CoV-2: Percentage of Participants with Seroresponse at Day 29, as Measured by PsVNA;Parts 1 and 2: Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs);Parts 1 and 2: Number of Participants With Unsolicited Adverse Events (AEs) and Severe AEs;Parts 1 and 2: Number of Participants With Unsolicited Medically Attended Adverse Events (MAAEs), Adverse Events of Special Interest (AESIs), Serious Adverse Events (SAEs), and AEs Leading to Discontinuation of Study

Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants With Unsocilited Medically Attended Adverse Events (MAAEs), Adverse Events of Special Interest (AESIs), Serious Adverse Events (SAEs), and AEs Leading to Discontinuation of Study;Number of Participants With Unsolicited Adverse Events (AEs) and Severe AEs

Number of Participants With Solicited Local and Systemic Adverse Reactions (ARs);Number of Participants With Unsocilited Medically Attended Adverse Events (MAAEs), Adverse Events of Special Interest (AESIs), Serious Adverse Events (SAEs), and AEs Leading to Discontinuation of Study;Number of Participants With Unsolicited Adverse Events (AEs) and Severe AEs