Baloxavir and Oseltamivir for the Treatment of Severe Influenza Infection in Immunocompromised Patients

Inclusion criteria: 1. Hematopoeitic cell transplant recipients OR hematological malignancy patients 2. Diagnosed with influenza ⱡ 3. Evidence of LRTI\* or high risk upper respiratory tract infection (URTI)\*\* ⱡ A positive multiplex PCR for influenza is required to confirm a diagnosis of influenza infection. \* LRTI will be defined as influenza cases that have evidence of disease below the level of the trachea on either imaging only (possible LRTI), imaging and microbiological evidence of lower airway disease with a bronchoscopy (probable LRTD) or pathological evidence of disease via biopsy (proven LRTI). \*\* High risk URI will be defined as those cases of influenza that do not have microbiological nor radiological evidence of LRTI, yet they have an immunodeficiency scoring index (ISI) of 3 or greater as defined by Shah D et al (19) for HCT recipients or severe neutropenia (ANC ≤500 cells/ml) and/or lymphopenia (ALC ≤200 cells/ml) for HM patients. Exclusion criteria: 1. Patient requires mechanical ventilation at time of enrollment 2. Patient is younger than the age of 12 years old 3. The patient is unable to tolerate oral therapy 4. The patient is pregnant at screening ( Positive serum β-HCG (beta-human chorionic gonadotropin) test for women of child-bearing potential). 5. The patient is on a prohibited medication. These include Influenza antiviral drugs with the exception of oseltamivir and baloxavir (such as peramivir, laninamivir, zanamivir, rimantadine, umifenovir or amantadine) and herbal therapies. 6. The patient is unable to consent will be excluded