This is a Phase I, open-label, uncontrolled, multi-country, multi-center, single-dose study. Initially, 2 cohorts of participants will be enrolled: 1) participants who are severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) negative at screening and have not knowingly been exposed to a SARS-CoV-2 positive individual (pre-exposure prophylaxis); and 2) participants who are SARS-CoV-2 RT-PCR positive at screening and have mild to moderate COVID-19 symptoms. A third cohort might be added for the treatment of severe COVID-19. If included, this third cohort will include participants who are SARS-CoV-2 positive at screening and have severe COVID-19.