inclusion criteria: * for low-risk participant arms 9-11 only: are greater than or equal to (≥)18 and less than (\<)65 years of age at the time of randomization and do not have the risk factors defined in the bullet point directly below * for high-risk participant arms 12 and 13 only: -- are ≥18 years of age and satisfy at least one of the following risk factors at the time of screening * are ≥65 years of age * have a body mass index (bmi) ≥ 35 * have chronic kidney disease * have type 1 or type 2 diabetes * have immunosuppressive disease * are currently receiving immunosuppressive treatment, or * are ≥55 years of age and have * cardiovascular disease, or * hypertension, or * chronic obstructive pulmonary disease or other chronic respiratory disease * for high-risk participant arms 12 and 13 only: * are 12-17 years of age (inclusive) and satisfy at least one of the following risk factors at the time of screening * have a bmi ≥85th percentile for their age and gender based on cdc growth charts, https://www.cdc.gov/growthcharts/clinical_charts.htm * have sickle cell disease * have congenital or acquired heart disease * have neurodevelopmental disorders, for example, cerebral palsy * have a medical-related technological dependence, for example, tracheostomy, gastrostomy, or positive pressure ventilation (not related to covid-19) * have asthma or reactive airway or other chronic respiratory disease that requires daily medication for control * have type 1 or type 2 diabetes * have chronic kidney disease * have immunosuppressive disease, or * are currently receiving immunosuppressive treatment. for high-risk participants arm 14 only: * are ≥12 years of age and satisfy at least one of the following risk factors at the time of screening are ≥65 years of age * are adults (≥18 years of age) with bmi \>25 kg/m2 , or if age 12-17, have bmi ≥85th percentile for their age and gender based on cdc growth charts * have chronic kidney disease * have type 1 or type 2 diabetes * have immunosuppressive disease * are currently receiving immunosuppressive treatment * have cardiovascular disease (including congenital heart disease) or hypertension * have chronic lung diseases (for example, chronic obstructive pulmonary disease, asthma \[moderate-to-severe\], interstitial lung disease, cystic fibrosis and pulmonary hypertension) * have sickle cell disease * have neurodevelopmental disorder (for example, cerebral palsy) or other conditions that confer medical complexity (for example, genetic or metabolic syndromes and severe congenital anomalies) * have a medical-related technological dependence (for example, tracheostomy, gastrostomy, or positive pressure ventilation \[not related to covid-19\] * are currently not hospitalized * have one or more mild or moderate covid-19 symptoms: fever, cough, sore throat, malaise, headache, muscle pain, gastrointestinal symptoms, or shortness of breath with exertion, nasal congestion or runny nose, new loss of smell, chills * must have sample taken for test confirming viral infection no more than 3 days prior to starting the drug infusion * are men or non-pregnant women who agree to contraceptive requirements * understand and agree to comply with planned study procedures * agree to the collection of nasopharyngeal swabs and venous blood * the participant or legally authorized representative give signed informed consent and/or assent

inclusion criteria: * for low-risk participant arms 9-11 only: are greater than or equal to (≥)18 and less than (\<)65 years of age at the time of randomization and do not have the risk factors defined in the bullet point directly below * for high-risk participant arms 12 and 13 only: -- are ≥18 years of age and satisfy at least one of the following risk factors at the time of screening * are ≥65 years of age * have a body mass index (bmi) ≥ 35 * have chronic kidney disease * have type 1 or type 2 diabetes * have immunosuppressive disease * are currently receiving immunosuppressive treatment, or * are ≥55 years of age and have * cardiovascular disease, or * hypertension, or * chronic obstructive pulmonary disease or other chronic respiratory disease * for high-risk participant arms 12 and 13 only: * are 12-17 years of age (inclusive) and satisfy at least one of the following risk factors at the time of screening * have a bmi ≥85th percentile for their age and gender based on cdc growth charts, https://www.cdc.gov/growthcharts/clinical_charts.htm * have sickle cell disease * have congenital or acquired heart disease * have neurodevelopmental disorders, for example, cerebral palsy * have a medical-related technological dependence, for example, tracheostomy, gastrostomy, or positive pressure ventilation (not related to covid-19) * have asthma or reactive airway or other chronic respiratory disease that requires daily medication for control * have type 1 or type 2 diabetes * have chronic kidney disease * have immunosuppressive disease, or * are currently receiving immunosuppressive treatment. for high-risk participants arm 14 only: * are ≥12 years of age and satisfy at least one of the following risk factors at the time of screening are ≥65 years of age * are adults (≥18 years of age) with bmi \>25 kg/m2 , or if age 12-17, have bmi ≥85th percentile for their age and gender based on cdc growth charts * have chronic kidney disease * have type 1 or type 2 diabetes * have immunosuppressive disease * are currently receiving immunosuppressive treatment * have cardiovascular disease (including congenital heart disease) or hypertension * have chronic lung diseases (for example, chronic obstructive pulmonary disease, asthma \[moderate-to-severe\], interstitial lung disease, cystic fibrosis and pulmonary hypertension) * have sickle cell disease * have neurodevelopmental disorder (for example, cerebral palsy) or other conditions that confer medical complexity (for example, genetic or metabolic syndromes and severe congenital anomalies) * have a medical-related technological dependence (for example, tracheostomy, gastrostomy, or positive pressure ventilation \[not related to covid-19\] * are currently not hospitalized * have one or more mild or moderate covid-19 symptoms: fever, cough, sore throat, malaise, headache, muscle pain, gastrointestinal symptoms, or shortness of breath with exertion, nasal congestion or runny nose, new loss of smell, chills * must have sample taken for test confirming viral infection no more than 3 days prior to starting the drug infusion * are men or non-pregnant women who agree to contraceptive requirements * understand and agree to comply with planned study procedures * agree to the collection of nasopharyngeal swabs and venous blood * the participant or legally authorized representative give signed informed consent and/or assent

inclusion criteria: - for low-risk participant arms 9-11 only: are greater than or equal to (≥)18 and less than (<)65 years of age at the time of randomization and do not have the risk factors defined in the bullet point directly below - for high-risk participant arms 12 and 13 only: -- are ≥18 years of age and satisfy at least one of the following risk factors at the time of screening - are ≥65 years of age - have a body mass index (bmi) ≥ 35 - have chronic kidney disease - have type 1 or type 2 diabetes - have immunosuppressive disease - are currently receiving immunosuppressive treatment, or - are ≥55 years of age and have - cardiovascular disease, or - hypertension, or - chronic obstructive pulmonary disease or other chronic respiratory disease - for high-risk participant arms 12 and 13 only: - are 12-17 years of age (inclusive) and satisfy at least one of the following risk factors at the time of screening - have a bmi ≥85th percentile for their age and gender based on cdc growth charts, https://www.cdc.gov/growthcharts/clinical_charts.htm - have sickle cell disease - have congenital or acquired heart disease - have neurodevelopmental disorders, for example, cerebral palsy - have a medical-related technological dependence, for example, tracheostomy, gastrostomy, or positive pressure ventilation (not related to covid-19) - have asthma or reactive airway or other chronic respiratory disease that requires daily medication for control - have type 1 or type 2 diabetes - have chronic kidney disease - have immunosuppressive disease, or - are currently receiving immunosuppressive treatment. for high-risk participants arm 14 only: - are ≥12 years of age and satisfy at least one of the following risk factors at the time of screening are ≥65 years of age - are adults (≥18 years of age) with bmi >25 kg/m2 , or if age 12-17, have bmi ≥85th percentile for their age and gender based on cdc growth charts - have chronic kidney disease - have type 1 or type 2 diabetes - have immunosuppressive disease - are currently receiving immunosuppressive treatment - have cardiovascular disease (including congenital heart disease) or hypertension - have chronic lung diseases (for example, chronic obstructive pulmonary disease, asthma [moderate-to-severe], interstitial lung disease, cystic fibrosis and pulmonary hypertension) - have sickle cell disease - have neurodevelopmental disorder (for example, cerebral palsy) or other conditions that confer medical complexity (for example, genetic or metabolic syndromes and severe congenital anomalies) - have a medical-related technological dependence (for example, tracheostomy, gastrostomy, or positive pressure ventilation [not related to covid-19] - are currently not hospitalized - have one or more mild or moderate covid-19 symptoms: fever, cough, sore throat, malaise, headache, muscle pain, gastrointestinal symptoms, or shortness of breath with exertion, nasal congestion or runny nose, new loss of smell, chills - must have sample taken for test confirming viral infection no more than 3 days prior to starting the drug infusion - are men or non-pregnant women who agree to contraceptive requirements - understand and agree to comply with planned study procedures - agree to the collection of nasopharyngeal swabs and venous blood - the participant or legally authorized representative give signed informed consent and/or assent

inclusion criteria: - for low-risk participant arms 9-11 only: are greater than or equal to (≥)18 and less than (<)65 years of age at the time of randomization and do not have the risk factors defined in the bullet point directly below - for high-risk participant arms 12 and 13 only: -- are ≥18 years of age and satisfy at least one of the following risk factors at the time of screening - are ≥65 years of age - have a body mass index (bmi) ≥ 35 - have chronic kidney disease - have type 1 or type 2 diabetes - have immunosuppressive disease - are currently receiving immunosuppressive treatment, or - are ≥55 years of age and have - cardiovascular disease, or - hypertension, or - chronic obstructive pulmonary disease or other chronic respiratory disease - for high-risk participant arms 12 and 13 only: - are 12-17 years of age (inclusive) and satisfy at least one of the following risk factors at the time of screening - have a bmi ≥85th percentile for their age and gender based on cdc growth charts, https://www.cdc.gov/growthcharts/clinical_charts.htm - have sickle cell disease - have congenital or acquired heart disease - have neurodevelopmental disorders, for example, cerebral palsy - have a medical-related technological dependence, for example, tracheostomy, gastrostomy, or positive pressure ventilation (not related to covid-19) - have asthma or reactive airway or other chronic respiratory disease that requires daily medication for control - have type 1 or type 2 diabetes - have chronic kidney disease - have immunosuppressive disease, or - are currently receiving immunosuppressive treatment. for high-risk participants arm 14 only: - are ≥12 years of age and satisfy at least one of the following risk factors at the time of screening are ≥65 years of age - are adults (≥18 years of age) with bmi >25 kg/m2 , or if age 12-17, have bmi ≥85th percentile for their age and gender based on cdc growth charts - have chronic kidney disease - have type 1 or type 2 diabetes - have immunosuppressive disease - are currently receiving immunosuppressive treatment - have cardiovascular disease (including congenital heart disease) or hypertension - have chronic lung diseases (for example, chronic obstructive pulmonary disease, asthma [moderate-to-severe], interstitial lung disease, cystic fibrosis and pulmonary hypertension) - have sickle cell disease - have neurodevelopmental disorder (for example, cerebral palsy) or other conditions that confer medical complexity (for example, genetic or metabolic syndromes and severe congenital anomalies) - have a medical-related technological dependence (for example, tracheostomy, gastrostomy, or positive pressure ventilation [not related to covid-19] - are currently not hospitalized - have one or more mild or moderate covid-19 symptoms: fever, cough, sore throat, malaise, headache, muscle pain, gastrointestinal symptoms, or shortness of breath with exertion, nasal congestion or runny nose, new loss of smell, chills - must have sample taken for test confirming viral infection no more than 3 days prior to starting the drug infusion - are men or non-pregnant women who agree to contraceptive requirements - understand and agree to comply with planned study procedures - agree to the collection of nasopharyngeal swabs and venous blood - the participant or legally authorized representative give signed informed consent and/or assent

inclusion criteria: - for low-risk participant arms only: are greater than or equal to (≥)18 and less than (<)65 years of age at the time of randomization and do not have the risk factors defined in the bullet point directly below - for high-risk participant arms only: -- are ≥18 years of age and satisfy at least one of the following risk factors at the time of screening - are ≥65 years of age - have a body mass index (bmi) ≥ 35 - have chronic kidney disease - have type 1 or type 2 diabetes - have immunosuppressive disease - are currently receiving immunosuppressive treatment, or - are ≥55 years of age and have - cardiovascular disease, or - hypertension, or - chronic obstructive pulmonary disease or other chronic respiratory disease - for high-risk participant arms only: -- are 12-17 years of age (inclusive) and satisfy at least one of the following risk factors at the time of screening - have a bmi ≥85th percentile for their age and gender based on cdc growth charts, https://www.cdc.gov/growthcharts/clinical_charts.htm - have sickle cell disease - have congenital or acquired heart disease - have neurodevelopmental disorders, for example, cerebral palsy - have a medical-related technological dependence, for example, tracheostomy, gastrostomy, or positive pressure ventilation (not related to covid-19) - have asthma or reactive airway or other chronic respiratory disease that requires daily medication for control - have type 1 or type 2 diabetes - have chronic kidney disease - have immunosuppressive disease, or - are currently receiving immunosuppressive treatment. - are currently not hospitalized - have one or more mild or moderate covid-19 symptoms: fever, cough, sore throat, malaise, headache, muscle pain, gastrointestinal symptoms, or shortness of breath with exertion, nasal congestion or runny nose, new loss of smell, chills - must have sample taken for test confirming viral infection no more than 3 days prior to starting the drug infusion - are men or non-pregnant women who agree to contraceptive requirements - understand and agree to comply with planned study procedures - agree to the collection of nasopharyngeal swabs and venous blood - the participant or legally authorized representative give signed informed consent and/or assent

inclusion criteria: - for low-risk participant arms only: are greater than or equal to (≥)18 and less than (<)65 years of age at the time of randomization and do not have the risk factors defined in the bullet point directly below - for high-risk participant arms only: -- are ≥18 years of age and satisfy at least one of the following risk factors at the time of screening - are ≥65 years of age - have a body mass index (bmi) ≥ 35 - have chronic kidney disease - have type 1 or type 2 diabetes - have immunosuppressive disease - are currently receiving immunosuppressive treatment, or - are ≥55 years of age and have - cardiovascular disease, or - hypertension, or - chronic obstructive pulmonary disease or other chronic respiratory disease - for high-risk participant arms only: -- are 12-17 years of age (inclusive) and satisfy at least one of the following risk factors at the time of screening - have a bmi ≥85th percentile for their age and gender based on cdc growth charts, https://www.cdc.gov/growthcharts/clinical_charts.htm - have sickle cell disease - have congenital or acquired heart disease - have neurodevelopmental disorders, for example, cerebral palsy - have a medical-related technological dependence, for example, tracheostomy, gastrostomy, or positive pressure ventilation (not related to covid-19) - have asthma or reactive airway or other chronic respiratory disease that requires daily medication for control - have type 1 or type 2 diabetes - have chronic kidney disease - have immunosuppressive disease, or - are currently receiving immunosuppressive treatment. - are currently not hospitalized - have one or more mild or moderate covid-19 symptoms: fever, cough, sore throat, malaise, headache, muscle pain, gastrointestinal symptoms, or shortness of breath with exertion, nasal congestion or runny nose, new loss of smell, chills - must have sample taken for test confirming viral infection no more than 3 days prior to starting the drug infusion - are men or non-pregnant women who agree to contraceptive requirements - understand and agree to comply with planned study procedures - agree to the collection of nasopharyngeal swabs and venous blood - the participant or legally authorized representative give signed informed consent and/or assent

inclusion criteria: - are currently not hospitalized - have one or more mild or moderate covid-19 symptoms: fever, cough, sore throat, malaise, headache, muscle pain, gastrointestinal symptoms, or shortness of breath with exertion - must have sample taken for test confirming viral infection no more than 3 days prior to starting the drug infusion - are men or non-pregnant women who agree to contraceptive requirements - understand and agree to comply with planned study procedures - agree to the collection of nasopharyngeal swabs and venous blood - the participant or legally authorized representative give signed informed consent

inclusion criteria: - are currently not hospitalized - have one or more mild or moderate covid-19 symptoms: fever, cough, sore throat, malaise, headache, muscle pain, gastrointestinal symptoms, or shortness of breath with exertion - must have sample taken for test confirming viral infection no more than 3 days prior to starting the drug infusion - are men or non-pregnant women who agree to contraceptive requirements - understand and agree to comply with planned study procedures - agree to the collection of nasopharyngeal swabs and venous blood - the participant or legally authorized representative give signed informed consent