IVIG in Patients With Severe COVID-19 Requiring Mechanical Ventilation

Inclusion Criteria: 1. Confirmed COVID-19 positive test result 2. Initiation of the first dose of IVIG within 72 hours of mechanical ventilation. 3. Age \>18 years old. 4. Consenting next of kin having access to an electronic device that is able to access DocuSign® online and email for consenting. 5. Subjects or their proxy must have the ability to understand the requirements of the study, provide informed consent, and provide authorization of use and disclosure of personal health information. Exclusion Criteria: 1. Superimposed bacterial pneumonia or bacteremia 2. Severe allergy to any IVIG product formulation 3. Hypersensitivity to corn 4. Uncontrolled hypertension (SBP\>180 mm Hg or DBP\>120mmHg) 5. Active participant in another research treatment study 6. Advanced dementia 7. Severe renal disease (CrCl\< 20 mL/min) 8. Active cancer malignancy 9. Active treatment with cancer chemotherapy or immunotherapy 10. Congestive heart failure clinically or by history (EF\< 25%) 11. Prior receipt during admission of any other investigational agent (eg. convalescent plasma, tocilizumab) 12. Venous or arterial thrombosis \< 90 days prior 13. Are receiving cytotoxic or biologic treatments such as TNF inhibitors, anti-interleukin-1 (IL-1), anti-IL-6 (tocilizumab or sarilumab), T-cell or B-cell targeted therapies (rituximab), interferon, or Janus kinase (JAK) inhibitors for any indication at study entry. Note: A washout period 4 weeks (or 5 half-lives, whichever is longer) is required prior to screening, with the following exceptions: * B-cell targeted therapies: a washout period of 24 weeks or 5 half-lives (whichever is longer) * TNF inhibitors: a washout period of 2 weeks or 5 half-lives (whichever is longer), and * JAK inhibitor: a washout period of 1 week or 5 half-lives (whichever is longer).