inclusion criteria: 1. 18 years of age or older; 2. diagnosed covid-19 disease with confirmed sars-cov-2 viral infection; 3. able to sign the informed consent form (icf) or next of kin/legal guardian able to sign informed consent; 4. randomization within 24 hours of intubation and mechanical ventilation due to respiratory failure from covid-19 infection; 5. absolute lymphocyte count \> 800 / mm3; 6. women of childbearing potential (wcbp) must have a negative urine or serum (if anuric) pregnancy test at screening; 7. wcbp must agree to abstain from sex or use an adequate method of contraception from the time of informed consent through day 28; 8. males must abstain from sex with wcbp or use an adequate method of contraception from the time of informed consent through day 28.

inclusion criteria: 1. 18 years of age or older; 2. diagnosed covid-19 disease with confirmed sars-cov-2 viral infection; 3. able to sign the informed consent form (icf) or next of kin/legal guardian able to sign informed consent; 4. randomization within 24 hours of intubation and mechanical ventilation due to respiratory failure from covid-19 infection; 5. absolute lymphocyte count \> 800 / mm3; 6. women of childbearing potential (wcbp) must have a negative urine or serum (if anuric) pregnancy test at screening; 7. wcbp must agree to abstain from sex or use an adequate method of contraception from the time of informed consent through day 28; 8. males must abstain from sex with wcbp or use an adequate method of contraception from the time of informed consent through day 28.

inclusion criteria: 18 years of age or older; diagnosed covid-19 disease with confirmed sars-cov-2 viral infection; able to sign the informed consent form (icf) or next of kin/legal guardian able to sign informed consent; randomization within 24 hours of intubation and mechanical ventilation due to respiratory failure from covid-19 infection; absolute lymphocyte count > 800 / mm3; women of childbearing potential (wcbp) must have a negative urine or serum (if anuric) pregnancy test at screening; wcbp must agree to abstain from sex or use an adequate method of contraception from the time of informed consent through day 28; males must abstain from sex with wcbp or use an adequate method of contraception from the time of informed consent through day 28.

inclusion criteria: 18 years of age or older; diagnosed covid-19 disease with confirmed sars-cov-2 viral infection; able to sign the informed consent form (icf) or next of kin/legal guardian able to sign informed consent; randomization within 24 hours of intubation and mechanical ventilation due to respiratory failure from covid-19 infection; absolute lymphocyte count > 800 / mm3; women of childbearing potential (wcbp) must have a negative urine or serum (if anuric) pregnancy test at screening; wcbp must agree to abstain from sex or use an adequate method of contraception from the time of informed consent through day 28; males must abstain from sex with wcbp or use an adequate method of contraception from the time of informed consent through day 28.

inclusion criteria: 1. 18 years of age or older; 2. diagnosed covid-19 disease with confirmed sars-cov-2 viral infection; 3. able to sign the informed consent form (icf) or next of kin/legal guardian able to sign informed consent; 4. randomization within 24 hours of intubation and mechanical ventilation due to respiratory failure from covid-19 infection; 5. absolute lymphocyte count > 800 / mm3; 6. women of childbearing potential (wcbp) must have a negative urine or serum (if anuric) pregnancy test at screening; 7. wcbp must agree to abstain from sex or use an adequate method of contraception from the time of informed consent through day 28; 8. males must abstain from sex with wcbp or use an adequate method of contraception from the time of informed consent through day 28.

inclusion criteria: 1. 18 years of age or older; 2. diagnosed covid-19 disease with confirmed sars-cov-2 viral infection; 3. able to sign the informed consent form (icf) or next of kin/legal guardian able to sign informed consent; 4. randomization within 24 hours of intubation and mechanical ventilation due to respiratory failure from covid-19 infection; 5. absolute lymphocyte count > 800 / mm3; 6. women of childbearing potential (wcbp) must have a negative urine or serum (if anuric) pregnancy test at screening; 7. wcbp must agree to abstain from sex or use an adequate method of contraception from the time of informed consent through day 28; 8. males must abstain from sex with wcbp or use an adequate method of contraception from the time of informed consent through day 28.