inclusion criteria: * participant was confirmed positive for the novel coronavirus responsible for sars-cov-2 (severe acute respiratory syndrome coronavirus 2) infection as determined by polymerase chain reaction (pcr) at screening * participant had a presumptive diagnosis of ards at screening and partial pressure of arterial oxygen (pao2)/fraction of inspired oxygen (fio2) (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen \[pf ratio\]) less than (\<) 300 prior to randomization * participant was intubated and receiving mechanical ventilation prior to randomization * participants must had initiated mechanical ventilation within 48 hours prior to screening, or had an immediate clinical plan for such intervention at time of screening * participant was likely to survive, in the opinion of the investigator, for at least 72 hours from the time of screening

inclusion criteria: * participant was confirmed positive for the novel coronavirus responsible for sars-cov-2 (severe acute respiratory syndrome coronavirus 2) infection as determined by polymerase chain reaction (pcr) at screening * participant had a presumptive diagnosis of ards at screening and partial pressure of arterial oxygen (pao2)/fraction of inspired oxygen (fio2) (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen \[pf ratio\]) less than (\<) 300 prior to randomization * participant was intubated and receiving mechanical ventilation prior to randomization * participants must had initiated mechanical ventilation within 48 hours prior to screening, or had an immediate clinical plan for such intervention at time of screening * participant was likely to survive, in the opinion of the investigator, for at least 72 hours from the time of screening

inclusion criteria: participant was confirmed positive for the novel coronavirus responsible for sars-cov-2 (severe acute respiratory syndrome coronavirus 2) infection as determined by polymerase chain reaction (pcr) at screening participant had a presumptive diagnosis of ards at screening and partial pressure of arterial oxygen (pao2)/fraction of inspired oxygen (fio2) (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen [pf ratio]) less than (<) 300 prior to randomization participant was intubated and receiving mechanical ventilation prior to randomization participants must had initiated mechanical ventilation within 48 hours prior to screening, or had an immediate clinical plan for such intervention at time of screening participant was likely to survive, in the opinion of the investigator, for at least 72 hours from the time of screening

inclusion criteria: participant was confirmed positive for the novel coronavirus responsible for sars-cov-2 (severe acute respiratory syndrome coronavirus 2) infection as determined by polymerase chain reaction (pcr) at screening participant had a presumptive diagnosis of ards at screening and partial pressure of arterial oxygen (pao2)/fraction of inspired oxygen (fio2) (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen [pf ratio]) less than (<) 300 prior to randomization participant was intubated and receiving mechanical ventilation prior to randomization participants must had initiated mechanical ventilation within 48 hours prior to screening, or had an immediate clinical plan for such intervention at time of screening participant was likely to survive, in the opinion of the investigator, for at least 72 hours from the time of screening

inclusion criteria: - participant has been confirmed positive for the novel coronavirus responsible for covid-19 (sars-cov-2) infection as determined by polymerase chain reaction (pcr) at screening - participant has a presumptive diagnosis of ards at screening and partial pressure of arterial oxygen (pao2)/fraction of inspired oxygen (fio2) (pf ratio) < 300 prior to randomization - participant is intubated and receiving mechanical ventilation prior to randomization - participants must have initiated mechanical ventilation within 48 hours prior to screening, or have an immediate clinical plan for such intervention at time of screening - participant is likely to survive, in the opinion of the investigator, for at least 72 hours from the time of screening

inclusion criteria: - participant has been confirmed positive for the novel coronavirus responsible for covid-19 (sars-cov-2) infection as determined by polymerase chain reaction (pcr) at screening - participant has a presumptive diagnosis of ards at screening and partial pressure of arterial oxygen (pao2)/fraction of inspired oxygen (fio2) (pf ratio) < 300 prior to randomization - participant is intubated and receiving mechanical ventilation prior to randomization - participants must have initiated mechanical ventilation within 48 hours prior to screening, or have an immediate clinical plan for such intervention at time of screening - participant is likely to survive, in the opinion of the investigator, for at least 72 hours from the time of screening