⁃ Subprotocol 1:

• ≥65 years of age at the time of signing the informed consent or ≥12 to \<65 years of age at the time of signing the informed consent with at least 1 risk factor for severe outcomes from COVID-19.

• Investigator's assessment that the participant understands and is willing and physically able to comply with protocol-mandated follow-up, including all procedures.

• Participants who are assigned female at birth or could become pregnant:

• i) Has a negative pregnancy test at the Screening Visit and on the day of vaccination prior to vaccine dose being administered on Day 1.

⁃ ii) Has practiced adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the first dose (Day 1).

⁃ iii) Has agreed to continue adequate contraception through 28 days following vaccine administration.