inclusion criteria: 1. a written, signed informed consent, or emergency oral consent, by the patient or the patient's legally authorized representative, and the anticipated ability for participant to be re-consented in the future for ongoing study participation 2. men and women aged ≥ 25 - 80 (included) years of age 3. hospitalized patients with two absolute lymphocyte count (alc) ≤ 1000 cells/mm3, at two time points at least 24 hours apart, following hospitalization: 4. hospitalized patients with moderate to severe hypoxemia requiring oxygen therapy at \>4l per minute nasal cannula or greater to keep saturations \>90%, non-invasive positive pressure ventilation (e.g., bipap), or patients intubated / ventilated for respiratory failure 5. confirmed infection with covid-19 by any acceptable test available / utilized at each site 6. willingness and ability to practice contraception regardless of the gender of the patient during 5 months after last drug exposure 7. private insurance or government / institution financial support (through cms or other)

inclusion criteria: 1. a written, signed informed consent, or emergency oral consent, by the patient or the patient's legally authorized representative, and the anticipated ability for participant to be re-consented in the future for ongoing study participation 2. men and women aged ≥ 25 - 80 (included) years of age 3. hospitalized patients with two absolute lymphocyte count (alc) ≤ 1000 cells/mm3, at two time points at least 24 hours apart, following hospitalization: 4. hospitalized patients with moderate to severe hypoxemia requiring oxygen therapy at \>4l per minute nasal cannula or greater to keep saturations \>90%, non-invasive positive pressure ventilation (e.g., bipap), or patients intubated / ventilated for respiratory failure 5. confirmed infection with covid-19 by any acceptable test available / utilized at each site 6. willingness and ability to practice contraception regardless of the gender of the patient during 5 months after last drug exposure 7. private insurance or government / institution financial support (through cms or other)

inclusion criteria: a written, signed informed consent, or emergency oral consent, by the patient or the patient's legally authorized representative, and the anticipated ability for participant to be re-consented in the future for ongoing study participation men and women aged ≥ 25 - 80 (included) years of age hospitalized patients with two absolute lymphocyte count (alc) ≤ 1000 cells/mm3, at two time points at least 24 hours apart, following hospitalization: hospitalized patients with moderate to severe hypoxemia requiring oxygen therapy at >4l per minute nasal cannula or greater to keep saturations >90%, non-invasive positive pressure ventilation (e.g., bipap), or patients intubated / ventilated for respiratory failure confirmed infection with covid-19 by any acceptable test available / utilized at each site willingness and ability to practice contraception regardless of the gender of the patient during 5 months after last drug exposure private insurance or government / institution financial support (through cms or other)

inclusion criteria: a written, signed informed consent, or emergency oral consent, by the patient or the patient's legally authorized representative, and the anticipated ability for participant to be re-consented in the future for ongoing study participation men and women aged ≥ 25 - 80 (included) years of age hospitalized patients with two absolute lymphocyte count (alc) ≤ 1000 cells/mm3, at two time points at least 24 hours apart, following hospitalization: hospitalized patients with moderate to severe hypoxemia requiring oxygen therapy at >4l per minute nasal cannula or greater to keep saturations >90%, non-invasive positive pressure ventilation (e.g., bipap), or patients intubated / ventilated for respiratory failure confirmed infection with covid-19 by any acceptable test available / utilized at each site willingness and ability to practice contraception regardless of the gender of the patient during 5 months after last drug exposure private insurance or government / institution financial support (through cms or other)

inclusion criteria: 1. a written, signed informed consent, or emergency oral consent, by the patient or the patient's legally authorized representative, and the anticipated ability for participant to be re-consented in the future for ongoing study participation 2. men and women aged ≥ 25 - 80 (included) years of age 3. hospitalized patients with two absolute lymphocyte count (alc) ≤ 1000 cells/mm3, at two time points at least 24 hours apart, following hospitalization: 4. hospitalized patients with moderate to severe hypoxemia requiring oxygen therapy at >4l per minute nasal cannula or greater to keep saturations >90%, non-invasive positive pressure ventilation (e.g., bipap), or patients intubated / ventilated for respiratory failure 5. confirmed infection with covid-19 by any acceptable test available / utilized at each site 6. willingness and ability to practice contraception regardless of the gender of the patient during 5 months after last drug exposure 7. private insurance or government / institution financial support (through cms or other)

inclusion criteria: 1. a written, signed informed consent, or emergency oral consent, by the patient or the patient's legally authorized representative, and the anticipated ability for participant to be re-consented in the future for ongoing study participation 2. men and women aged ≥ 25 - 80 (included) years of age 3. hospitalized patients with two absolute lymphocyte count (alc) ≤ 1000 cells/mm3, at two time points at least 24 hours apart, following hospitalization: 4. hospitalized patients with moderate to severe hypoxemia requiring oxygen therapy at >4l per minute nasal cannula or greater to keep saturations >90%, non-invasive positive pressure ventilation (e.g., bipap), or patients intubated / ventilated for respiratory failure 5. confirmed infection with covid-19 by any acceptable test available / utilized at each site 6. willingness and ability to practice contraception regardless of the gender of the patient during 5 months after last drug exposure 7. private insurance or government / institution financial support (through cms or other)