The study researchers think that a medication called N-acetylcysteine can help fight the COVID-19 virus by boosting a type of cell in your immune system that attacks infections. By helping your immune system fight the virus, the researchers think that the infection will get better, which could allow the patient to be moved out of the critical care unit or go off a ventilator, or prevent them from moving into a critical care unit or going on a ventilator.

The US Food and Drug Administration (FDA) has approved N-acetylcysteine to treat the liver side effects resulting from an overdose of the anti-inflammatory medication Tylenol® (acetaminophen). N-acetylcysteine is also used to loosen the thick mucus in the lungs of people with cystic fibrosis or chronic obstructive pulmonary disease (COPD). This study is the first to test N-acetylcysteine in people with severe COVID-19 infections.

Inclusion Criteria:

• Documented COVID-19 infection (either performed on site or documented external report)
• Age ≥ 18

Arm A:

• Admission to an intensive care unit at MSK (M-11) and/or receiving mechanical ventilation
• Absolute lymphocyte count ≤ 1.0/mm3
• As the ALC of patients with lymphoid malignancies is unreliable, they may be enrolled at the discretion of the treating physician after review of their blood work.

Arm B:

• Arm B:Requiring 2L or more of supplemental oxygen by nasal cannula or higher to maintain SpO2 of 95%

Exclusion Criteria:

Arm B:

• requiring mechanical ventilation or admission to an intensive care unit at MSK (M11)

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.