* ongoing or prior participation in any other clinical trial of an experimental vaccine or treatment for covid-19 * prior or current hospitalization for covid-19 or need for hospitalization * treatment of covid-19 with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) rdv or administration of any sars-cov-2 (or covid-19) vaccine * participants chronically administered chloroquine or hydroxychloroquine for any reason are to be excluded * requiring oxygen supplementation * positive pregnancy test * breastfeeding female * known hypersensitivity to the study treatment, its metabolites, or formulation excipient * pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

* ongoing or prior participation in any other clinical trial of an experimental vaccine or treatment for covid-19 * prior or current hospitalization for covid-19 or need for hospitalization * treatment of covid-19 with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) rdv or administration of any sars-cov-2 (or covid-19) vaccine * participants chronically administered chloroquine or hydroxychloroquine for any reason are to be excluded * requiring oxygen supplementation * positive pregnancy test * breastfeeding female * known hypersensitivity to the study treatment, its metabolites, or formulation excipient * pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

ongoing or prior participation in any other clinical trial of an experimental vaccine or treatment for covid-19 prior or current hospitalization for covid-19 or need for hospitalization treatment of covid-19 with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) rdv or administration of any sars-cov-2 (or covid-19) vaccine participants chronically administered chloroquine or hydroxychloroquine for any reason are to be excluded requiring oxygen supplementation positive pregnancy test breastfeeding female known hypersensitivity to the study treatment, its metabolites, or formulation excipient pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

ongoing or prior participation in any other clinical trial of an experimental vaccine or treatment for covid-19 prior or current hospitalization for covid-19 or need for hospitalization treatment of covid-19 with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) rdv or administration of any sars-cov-2 (or covid-19) vaccine participants chronically administered chloroquine or hydroxychloroquine for any reason are to be excluded requiring oxygen supplementation positive pregnancy test breastfeeding female known hypersensitivity to the study treatment, its metabolites, or formulation excipient pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

- ongoing or prior participation in any other clinical trial of an experimental vaccine or treatment for covid-19 - prior or current hospitalization for covid-19 or need for hospitalization - treatment of covid-19 with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) remdesivir (rdv) or administration of any sars-cov-2 (or covid-19) vaccine - patients chronically administered chloroquine or hydroxychloroquine for any reason are to be excluded - requiring oxygen supplementation - positive pregnancy test - breastfeeding female - known hypersensitivity to the study treatment, its metabolites, or formulation excipient - pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

- ongoing or prior participation in any other clinical trial of an experimental vaccine or treatment for covid-19 - prior or current hospitalization for covid-19 or need for hospitalization - treatment of covid-19 with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) remdesivir (rdv) or administration of any sars-cov-2 (or covid-19) vaccine - patients chronically administered chloroquine or hydroxychloroquine for any reason are to be excluded - requiring oxygen supplementation - positive pregnancy test - breastfeeding female - known hypersensitivity to the study treatment, its metabolites, or formulation excipient - pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

- ongoing or prior participation in any other clinical trial of an experimental vaccine or treatment for covid-19 - prior or current hospitalization for covid-19 or need for hospitalization - concurrent or planned treatment of covid-19 with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) remdesivir (rdv) - patients chronically administered chloroquine or hydroxychloroquine for any reason are to be excluded - requiring oxygen supplementation - positive pregnancy test - breastfeeding female - known hypersensitivity to the study treatment, its metabolites, or formulation excipient - pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

- ongoing or prior participation in any other clinical trial of an experimental vaccine or treatment for covid-19 - prior or current hospitalization for covid-19 or need for hospitalization - concurrent or planned treatment of covid-19 with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) remdesivir (rdv) - patients chronically administered chloroquine or hydroxychloroquine for any reason are to be excluded - requiring oxygen supplementation - positive pregnancy test - breastfeeding female - known hypersensitivity to the study treatment, its metabolites, or formulation excipient - pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

- ongoing or prior participation in any other clinical trial of an experimental treatment for covid-19 - prior or current hospitalization for covid-19 or need for hospitalization - concurrent or planned treatment with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) remdesivir (rdv) - requiring oxygen supplementation - positive pregnancy test - breastfeeding female - known hypersensitivity to the study treatment, its metabolites, or formulation excipient - pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.

- ongoing or prior participation in any other clinical trial of an experimental treatment for covid-19 - prior or current hospitalization for covid-19 or need for hospitalization - concurrent or planned treatment with other agents with actual or possible direct antiviral activity against sars-cov-2 including intravenous (iv) remdesivir (rdv) - requiring oxygen supplementation - positive pregnancy test - breastfeeding female - known hypersensitivity to the study treatment, its metabolites, or formulation excipient - pre-existing pulmonary conditions such as chronic obstructive pulmonary disease or asthma (parts a and b only) note: other protocol defined inclusion/exclusion criteria may apply.