Emerging SARS-CoV-2 variants impacting susceptibility to study drug

The primary objectives of the study are:

• To characterize the concentrations of casirivimab+imdevimab in serum over time
• To evaluate the safety and tolerability of casirivimab+imdevimab

The secondary objective of the study is:

• To assess the immunogenicity of casirivimab+imdevimab

Key Inclusion Criteria:

1. Has SARS-CoV-2 positive antigen or molecular diagnostic test ≤72 hours prior to study enrollment Note: historical record of positive result is acceptable as long as the sample was collected ≤72 hours prior to enrollment
2. Has symptoms consistent with COVID-19, as determined by the investigator, with onset ≤ 14 days before dosing
3. Hospitalized due to COVID-19
4. Provide informed consent signed by study patient or legally acceptable representative/guardian

Key Exclusion Criteria:

1. In the opinion of the investigator, unlikely to survive for >96 hours from screening

2. Neonates having gestational age of <29 weeks and weight <1.1 kg

3. Receiving extracorporeal membrane oxygenation (ECMO)

4. Has new-onset stroke or seizure disorder during hospitalization

5. Initiated on renal replacement therapy due to COVID-19

6. Has circulatory shock requiring vasopressors on dosing day Note: Patients who require vasopressors for sedation-related hypotension or reasons other than circulatory shock may be eligible in this study

7. Participation in a clinical research study, including any double-blind study, evaluating an investigational product within 30 days and less than 5 half-lives of the investigational product prior to the screening visit

8. Members of the clinical site study team and/or their immediate family

9. Plans to receive an investigational or approved SARS-CoV-2 vaccine within 90 days after study drug administration based on current Centers for Disease Control vaccination guidelines (CDC, 2021). Refer to the latest CDC guidance for any updates.

   Note: Patients who have already completed vaccination prior to study enrollment may be allowed in the study.

10. Prior use (within 90 days prior to study drug administration) or current use of any investigational, authorized, or approved passive antibody for prophylaxis of SARS-CoV-2 infection, including convalescent plasma, convalescent sera, hyperimmune globulin, or other monoclonal antibodies (eg, bamlanivimab and etesevimab, sotrovimab)

Note: Other protocol defined Inclusion/ Exclusion criteria apply

All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing

When Regeneron has received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication, has made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry), has the legal authority to share the data, and has ensured the ability to protect participant privacy.

Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf