• Laboratory-confirmed mpox infection as determined by PCR obtained from blood, oropharynx, or skin lesion within 48 hours of screening

• Mpox illness of any duration provided that the patient has at least one active, not yet scabbed, lesion

• Stated willingness to comply with all study procedures (including required inpatient stay) and availability for the duration of the study

• Ability to provide informed consent personally or by a legally or culturally acceptable representative if the patient is unable to do so

• Severe disease, defined as the presence of at least one of the following:

‣ Flat lesions (flat and soft lesions; no pustules or vesicles visible to the eye)

⁃ Pregnancy (due to risk of serious complication)

⁃ Suspected sickle cell disease

⁃ Severe clinical disease, defined as having at least 3 of the following:

• Lesion count greater than 250

∙ Fever for greater than 48 hours

∙ Hypotension (systolic blood pressure less than 90 mmHg or diastolic blood pressure less than 60 mmHg)

∙ Pallor

∙ Respiratory distress

∙ Altered mental status

∙ Extreme lethargy

∙ Painful oral lesions making oral intake difficult

∙ Difficulty peeing or pooping due to painful lesions

∙ Painful lesions on hands and feet

∙ Tachycardia (heart rate greater than 100 beats per minute)

∙ Diarrhea (greater than or equal to 3 liquid stools per 24 hours)