key inclusion criteria: * has sars-cov-2-positive diagnostic test (from a sample collected ≤72 hours prior to randomization, using a validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, and an appropriate sample such as nasopharyngeal \[np\], nasal, oropharyngeal \[op\], or saliva) * has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization * maintains o2 saturation ≥93% on room air * is able to understand and complete study-related questionnaires (patients aged ≥12 years only) key

key inclusion criteria: * has sars-cov-2-positive diagnostic test (from a sample collected ≤72 hours prior to randomization, using a validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, and an appropriate sample such as nasopharyngeal \[np\], nasal, oropharyngeal \[op\], or saliva) * has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization * maintains o2 saturation ≥93% on room air * is able to understand and complete study-related questionnaires (patients aged ≥12 years only) key

key inclusion criteria: - has sars-cov-2-positive diagnostic test (from a sample collected ≤72 hours prior to randomization, using a validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, and an appropriate sample such as nasopharyngeal [np], nasal, oropharyngeal [op], or saliva) - has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization - maintains o2 saturation ≥93% on room air - is able to understand and complete study-related questionnaires (patients aged ≥12 years only) key

key inclusion criteria: - has sars-cov-2-positive diagnostic test (from a sample collected ≤72 hours prior to randomization, using a validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, and an appropriate sample such as nasopharyngeal [np], nasal, oropharyngeal [op], or saliva) - has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization - maintains o2 saturation ≥93% on room air - is able to understand and complete study-related questionnaires (patients aged ≥12 years only) key

key inclusion criteria: - has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization. a historical record of positive result is acceptable as long as the sample was collected ≤72 hours prior to randomization - (cohort 1): has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization, or - (cohort 2): has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization, or is asymptomatic at randomization and has no prior symptoms consistent with covid-19 (as determined by the investigator) - maintains o2 saturation ≥93% on room air - is able to understand and complete study-related questionnaires (cohort 1 and cohort 2 patients aged ≥12 years only) key

key inclusion criteria: - has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization. a historical record of positive result is acceptable as long as the sample was collected ≤72 hours prior to randomization - (cohort 1): has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization, or - (cohort 2): has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization, or is asymptomatic at randomization and has no prior symptoms consistent with covid-19 (as determined by the investigator) - maintains o2 saturation ≥93% on room air - is able to understand and complete study-related questionnaires (cohort 1 and cohort 2 patients aged ≥12 years only) key

key inclusion criteria: - has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization. a historical record of positive result from test conducted ≤72 hours prior to randomization is acceptable - meets 1 of the following 2 criteria: 1. symptomatic cohort (all phases): has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization or 2. asymptomatic cohort (phase 2): meets all of the following: - has had no symptoms consistent with covid-19 (as determined by the investigator) occurring at any time <2 months prior to randomization - has had no positive sars-cov-2 test results from a sample collected >7 days prior to randomization - has had no known contact (of any duration) with an individual who has confirmed covid-19 or confirmed positive sars-cov-2 test result >14 days prior to randomization. - has experienced covid-19 symptoms for <7 days - has symptoms consistent with covid-19, as determined by investigator, with onset ≤7 days before randomization key

key inclusion criteria: - has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization. a historical record of positive result from test conducted ≤72 hours prior to randomization is acceptable - meets 1 of the following 2 criteria: 1. symptomatic cohort (all phases): has symptoms consistent with covid-19, as determined by the investigator, with onset ≤7 days before randomization or 2. asymptomatic cohort (phase 2): meets all of the following: - has had no symptoms consistent with covid-19 (as determined by the investigator) occurring at any time <2 months prior to randomization - has had no positive sars-cov-2 test results from a sample collected >7 days prior to randomization - has had no known contact (of any duration) with an individual who has confirmed covid-19 or confirmed positive sars-cov-2 test result >14 days prior to randomization. - has experienced covid-19 symptoms for <7 days - has symptoms consistent with covid-19, as determined by investigator, with onset ≤7 days before randomization key