A physician may decide to request use of an investigational antiviral product through a single-patient Emergency Investigational New Drug (EIND) application if:

the physician considers the product may be urgently needed for the patient’s serious or life-threatening condition;
no satisfactory alternative therapy is available; and
the patient cannot receive the product through any existing clinical trials or expanded access protocols

https://www.fda.gov/drugs/investigational-new-drug-ind-application/emergency-investigational-new-drug-eind-applications-antiviral-products