Inclusion Criteria:  Tests negative for current or previous SARS-CoV-2 infection by RT PCR and serology (Pre-exposure population only)  Is at high risk of SARS-CoV-2 infection as assessed by the Investigator:  Post-exposure population: including, but not limited, to household contact or occupational/recreational exposure to an individual with a diagnosis of SARS-CoV-2 infection (index case). Note: Participants with recent exposure to a laboratory-confirmed index case must be asymptomatic and randomized within 5 days (120 hours) of collection of the index case's positive SARS-CoV-2 diagnostic test. Pre-exposure population: Occupational, housing, recreational and/or social conditions that are likely to increase risk of exposure to SARS-CoV-2. Agrees to defer receipt of COVID-19 vaccination for minimum of 180 days (6 months) after dosing  Exclusion Criteria:  Has received (1) a SARS-CoV-2 vaccine, (2) mAb or (3) convalescent plasma from a person who has recovered from COVID-19 or prior participation in SARS-CoV2 vaccine, convalescent plasma, or mAb clinical trial any time prior to participation in the study. Receipt of any investigational product within 30 days or 5 half lives before the day of enrollment. Is acutely ill or febrile 72 hours before or at Screening or has other COVID-19 symptoms including cough, fatigue, muscle or body aches, headache, or loss of taste or smell. Fever is defined as a body temperature ≥38.0°C (≥100.4°F). Has received or plans to receive a non-COVID-19 vaccine within 28 days before or after dosing (except for seasonal influenza vaccine, which is not permitted within 14 days before or after dosing).  NOTE: Other protocol defined inclusion/exclusion criteria apply