SSA

Inclusion Criteria:

- Received at least 3 prior doses of a US-authorized mRNA COVID-19 vaccine, with the
most recent dose being a US-authorized Omicron BA.4/BA.5-adapted bivalent vaccine
received at least 150 days before Visit 1 (Day 1).

- 12 years of age and older

- Healthy participants (stable pre-existing disease permitted).

- Willing and able to comply with all scheduled visits/contacts, study procedures and
lifestyle considerations.

- Capable of giving, or parent(s)/legal guardian capable of giving, signed informed
consent.

Exclusion Criteria

- History of severe adverse reaction associated with a vaccine and/or severe allergic
reaction (eg, anaphylaxis) to any component of the study vaccines.

- Immunocompromised with known or suspected immunodeficiency, as determined by history
and/or laboratory/physical examination.

- Bleeding diathesis or condition associated with prolonged bleeding that would, in
the opinion of the investigator, contraindicate intramuscular injection.

- Women who are pregnant or breastfeeding.

- Any medical or psychiatric condition, or laboratory abnormality that may increase
the risk of study participation or, in the investigator's judgment, make the
participant inappropriate for the study.

- History of myocarditis or pericarditis.

- Receipt of systemic treatment with known immunosuppressant medications (including
cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune
disease), or radiotherapy, within 60 days before enrollment or planned receipt
through conclusion of the study.

- Receipt of blood/plasma products, immunoglobulin, or monoclonal antibodies, used for
the treatment or prevention of COVID-19 or those that are considered
immunosuppressive, from 60 days before study vaccination or planned receipt
throughout the study.

- Participation in other studies involving receipt of other study intervention within
28 days before enrollment. Anticipated participation in other studies involving
other study intervention from enrollment through the end of this study.

- Investigator site staff directly involved in the conduct of the study and their
family members, site staff otherwise supervised by the investigator, and sponsor and
sponsor delegate employees directly involved in the conduct of the study and their
family members.

SSB

Inclusion Criteria:

- COVID-19 vaccine-naïve.

- Any positive SARS-CoV-2 test result >28 days before study intervention
administration.

- 12 years of age and older.

- Healthy participants (stable pre-existing disease permitted).

- Willing and able to comply with all scheduled visits/contacts, study procedures and
lifestyle considerations.

- Capable of giving or parent(s)/legal guardian capable of giving, signed informed
consent.

Exclusion Criteria:

- History of severe adverse reaction associated with a vaccine and/or severe allergic
reaction (eg, anaphylaxis) to any component of the study vaccines.

- Immunocompromised individuals with known or suspected immunodeficiency, as
determined by history and/or laboratory/physical examination.

- Bleeding diathesis or condition associated with prolonged bleeding that would, in
the opinion of the investigator, contraindicate intramuscular injection.

- Women who are pregnant or breastfeeding.

- Any medical or psychiatric condition, including recent (within the past year) or
active suicidal ideation/behavior, or laboratory abnormality that may increase the
risk of study participation or, in the investigator's judgment, make the participant
inappropriate for the study.

- History of myocarditis or pericarditis.

- Receipt of systemic treatment with known immunosuppressant medications (including
cytotoxic agents or systemic corticosteroids*, eg, for cancer or an autoimmune
disease), or radiotherapy, within 60 days before enrollment or planned receipt
through conclusion of the study.

- Receipt of blood/plasma products, immunoglobulin, or monoclonal antibodies used for
the treatment or prevention of COVID-19 or those that are considered
immunosuppressive, from 60 days before study intervention administration or planned
receipt throughout the study.

- Participation in other studies involving receipt of other study intervention within
28 days before enrollment. Anticipated participation in other studies involving
other study intervention from enrollment through the end of this study.

- Investigator site staff directly involved in the conduct of the study and their
family members, site staff otherwise supervised by the investigator, and sponsor and
sponsor delegate employees directly involved in the conduct of the study and their
family members.

SSC

Inclusion Criteria:

- Cohort 1: 18 years of age and older

- Cohort 2: 12 years of age and older

- Cohort 3: 18 years of age and older

- Healthy participants (stable pre-existing disease permitted).

- Willing and able to comply with all scheduled visits/contacts, study procedures and
lifestyle considerations.

- Capable of giving, or parent(s)/legal guardian capable of giving, signed informed
consent.

Exclusion Criteria

- History of severe adverse reaction associated with a vaccine and/or severe allergic
reaction (eg, anaphylaxis) to any component of the study vaccines.

- Immunocompromised with known or suspected immunodeficiency, as determined by history
and/or laboratory/physical examination.

- Bleeding diathesis or condition associated with prolonged bleeding that would, in
the opinion of the investigator, contraindicate intramuscular injection.

- Women who are pregnant or breastfeeding.

- Any medical or psychiatric condition, or laboratory abnormality that may increase
the risk of study participation or, in the investigator's judgment, make the
participant inappropriate for the study.

- History of myocarditis or pericarditis.

- Receipt of systemic treatment with known immunosuppressant medications (including
cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune
disease), or radiotherapy, within 60 days before enrollment or planned receipt
through conclusion of the study.

- Receipt of blood/plasma products, immunoglobulin, or monoclonal antibodies, used for
the treatment or prevention of COVID-19 or those that are considered
immunosuppressive, from 60 days before study vaccination or planned receipt
throughout the study.

- Receipt of a COVID-19 vaccine less than 150 days before study intervention
administration Visit 1 (Day 1).

- Participation in other studies involving receipt of other study intervention within
28 days before enrollment. Anticipated participation in other studies involving
other study intervention from enrollment through the end of this study.

- Investigator site staff directly involved in the conduct of the study and their
family members, site staff otherwise supervised by the investigator, and sponsor and
sponsor delegate employees directly involved in the conduct of the study and their
family members.