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: 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

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: 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

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

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

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: 1. 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. 2. 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

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: 1. 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. 2. 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