inclusion criteria: 1. willing and able to provide written informed consent, or with a legal representative who can provide informed consent, or enrolled under international conference on harmonization (ich) e6(r2) 4.8.15 emergency use provisions as deemed necessary by the investigator (age ≥18), or willing and able to provide assent (age ≥12 to \<18, where locally and nationally approved) prior to performing study procedures 2. patient is aged at least 18 years, enrollment of patients \< 65 years old will be limited to 20% of the total with the first 50% of enrollment conducted solely among those patients ≥ 55 years old. 3. patient has sars-cov-2 pneumonia from covid-19 infection of moderate to serious severity (who ordinal scale for clinical improvement score of 4 or 5) 4. patient has covid-19 symptoms ≤ 10 days and at least 1 of the following: * radiographic infiltrates by imaging (chest x-ray, ct scan, etc.) * o2 saturation (spo2) ≤ 94% on room air * requiring supplemental o2 (patients on hfno ≤ 20 l/min with fio2 \< 0.5 are allowed), but not requiring mechanical ventilation. note: patients admitted with immediate need for mechanical ventilation are of a severity too critical for inclusion into this protocol. patients who are already in the hospital and have been removed from mechanical ventilation are not eligible.

inclusion criteria: 1. willing and able to provide written informed consent, or with a legal representative who can provide informed consent, or enrolled under international conference on harmonization (ich) e6(r2) 4.8.15 emergency use provisions as deemed necessary by the investigator (age ≥18), or willing and able to provide assent (age ≥12 to \<18, where locally and nationally approved) prior to performing study procedures 2. patient is aged at least 18 years, enrollment of patients \< 65 years old will be limited to 20% of the total with the first 50% of enrollment conducted solely among those patients ≥ 55 years old. 3. patient has sars-cov-2 pneumonia from covid-19 infection of moderate to serious severity (who ordinal scale for clinical improvement score of 4 or 5) 4. patient has covid-19 symptoms ≤ 10 days and at least 1 of the following: * radiographic infiltrates by imaging (chest x-ray, ct scan, etc.) * o2 saturation (spo2) ≤ 94% on room air * requiring supplemental o2 (patients on hfno ≤ 20 l/min with fio2 \< 0.5 are allowed), but not requiring mechanical ventilation. note: patients admitted with immediate need for mechanical ventilation are of a severity too critical for inclusion into this protocol. patients who are already in the hospital and have been removed from mechanical ventilation are not eligible.

inclusion criteria: willing and able to provide written informed consent, or with a legal representative who can provide informed consent, or enrolled under international conference on harmonization (ich) e6(r2) 4.8.15 emergency use provisions as deemed necessary by the investigator (age ≥18), or willing and able to provide assent (age ≥12 to <18, where locally and nationally approved) prior to performing study procedures patient is aged at least 18 years, enrollment of patients < 65 years old will be limited to 20% of the total with the first 50% of enrollment conducted solely among those patients ≥ 55 years old. patient has sars-cov-2 pneumonia from covid-19 infection of moderate to serious severity (who ordinal scale for clinical improvement score of 4 or 5) patient has covid-19 symptoms ≤ 10 days and at least 1 of the following: radiographic infiltrates by imaging (chest x-ray, ct scan, etc.) o2 saturation (spo2) ≤ 94% on room air requiring supplemental o2 (patients on hfno ≤ 20 l/min with fio2 < 0.5 are allowed), but not requiring mechanical ventilation. note: patients admitted with immediate need for mechanical ventilation are of a severity too critical for inclusion into this protocol. patients who are already in the hospital and have been removed from mechanical ventilation are not eligible.

inclusion criteria: willing and able to provide written informed consent, or with a legal representative who can provide informed consent, or enrolled under international conference on harmonization (ich) e6(r2) 4.8.15 emergency use provisions as deemed necessary by the investigator (age ≥18), or willing and able to provide assent (age ≥12 to <18, where locally and nationally approved) prior to performing study procedures patient is aged at least 18 years, enrollment of patients < 65 years old will be limited to 20% of the total with the first 50% of enrollment conducted solely among those patients ≥ 55 years old. patient has sars-cov-2 pneumonia from covid-19 infection of moderate to serious severity (who ordinal scale for clinical improvement score of 4 or 5) patient has covid-19 symptoms ≤ 10 days and at least 1 of the following: radiographic infiltrates by imaging (chest x-ray, ct scan, etc.) o2 saturation (spo2) ≤ 94% on room air requiring supplemental o2 (patients on hfno ≤ 20 l/min with fio2 < 0.5 are allowed), but not requiring mechanical ventilation. note: patients admitted with immediate need for mechanical ventilation are of a severity too critical for inclusion into this protocol. patients who are already in the hospital and have been removed from mechanical ventilation are not eligible.

inclusion criteria: 1. willing and able to provide written informed consent, or with a legal representative who can provide informed consent, or enrolled under international conference on harmonization (ich) e6(r2) 4.8.15 emergency use provisions as deemed necessary by the investigator (age ≥18), or willing and able to provide assent (age ≥12 to <18, where locally and nationally approved) prior to performing study procedures 2. patient is aged at least 18 years, enrollment of patients < 65 years old will be limited to 20% of the total with the first 50% of enrollment conducted solely among those patients ≥ 55 years old. 3. patient has sars-cov-2 pneumonia from covid-19 infection of moderate to serious severity (who ordinal scale for clinical improvement score of 4 or 5) 4. patient has covid-19 symptoms ≤ 10 days and at least 1 of the following: - radiographic infiltrates by imaging (chest x-ray, ct scan, etc.) - o2 saturation (spo2) ≤ 94% on room air - requiring supplemental o2 (patients on hfno ≤ 20 l/min with fio2 < 0.5 are allowed), but not requiring mechanical ventilation. note: patients admitted with immediate need for mechanical ventilation are of a severity too critical for inclusion into this protocol. patients who are already in the hospital and have been removed from mechanical ventilation are not eligible.

inclusion criteria: 1. willing and able to provide written informed consent, or with a legal representative who can provide informed consent, or enrolled under international conference on harmonization (ich) e6(r2) 4.8.15 emergency use provisions as deemed necessary by the investigator (age ≥18), or willing and able to provide assent (age ≥12 to <18, where locally and nationally approved) prior to performing study procedures 2. patient is aged at least 18 years, enrollment of patients < 65 years old will be limited to 20% of the total with the first 50% of enrollment conducted solely among those patients ≥ 55 years old. 3. patient has sars-cov-2 pneumonia from covid-19 infection of moderate to serious severity (who ordinal scale for clinical improvement score of 4 or 5) 4. patient has covid-19 symptoms ≤ 10 days and at least 1 of the following: - radiographic infiltrates by imaging (chest x-ray, ct scan, etc.) - o2 saturation (spo2) ≤ 94% on room air - requiring supplemental o2 (patients on hfno ≤ 20 l/min with fio2 < 0.5 are allowed), but not requiring mechanical ventilation. note: patients admitted with immediate need for mechanical ventilation are of a severity too critical for inclusion into this protocol. patients who are already in the hospital and have been removed from mechanical ventilation are not eligible.