• Is an adult ≥18 years of age at time of screening.

• Has completed any WHO/FDA-authorized or approved primary COVID-19 vaccination series.

• Has received last COVID-19 vaccine no less than 6 months prior to study enrollment (study vaccination).

• If a female of childbearing potential who is sexually active, agrees to use an adequate method of birth control from Screening through 90 days after last study vaccination, and has used an adequate birth control method for at least 30 days prior to Screening.

⁃ A. Female of childbearing potential is defined as post onset menarche and pre-menopausal person capable of becoming pregnant. This does not include females who meet any of the following conditions: a) menopausal \>2 years; b) tubal ligation \>1 year; c) bilateral salpingo-oophorectomy; or d) hysterectomy.

⁃ B. Adequate contraception is defined as a contraceptive method with a failure rate of less than 1% per year when used consistently and correctly and when applicable, in accordance with the product label. Examples include: oral contraceptives, either combined or progestogen alone; injectable progestogen; implants of etonogestrel or levonorgestrel; estrogenic vaginal ring; percutaneous contraceptive patches; intrauterine device or intrauterine system; the female participant has exclusively female sexual partners; partner is sterile or otherwise unable to produce sperm (information on the person's sterility can come from the site personnel's review of the participant's medical records or interview with the participant regarding her medical history); male condom combined with a vaginal spermicide (foam, gel, film, cream, or suppository); or male condom combined with a female diaphragm, either with or without a vaginal spermicide (foam, gel, film, cream, or suppository).

• Is medically stable, as determined by the site investigator (based on review of health status, vital signs, medical history, and physical examination).

• Agrees to not participate in any other SARS-CoV-2 infection prevention trial (vaccine, drug, biologic, or pre-exposure prophylaxis \[PrEP\]) during participation in the study.

• Willing and able to provide informed consent prior to initiation of study procedures.

• Is available for all study visits, willing to participate in all study procedures, and not planning to relocate from the area for the duration of the study.