Baloxavir in Combination With Oseltamivir in Allogenic Bone Marrow Transplant Recipients With Influenza

Inclusion Criteria: * Adult patients: Signed informed consent by any patient capable of giving consent, or, where the patient is not capable of giving consent, by his or her legal/authorized representative * Age greater than or equal to 18 years at the time of signing the Informed Consent Form/Assent Form * Ability to comply with the study protocol, in the investigator's judgment * Have received allogeneic bone marrow transplant * Tested positive for influenza infection after the onset of symptoms using a polymerase chain reaction (PCR)-based diagnostic assay. * Presence of (a) fever (≥38.0 °C per tympanic or rectal thermometer; ≥ 37.5 °C per axillary, oral or forehead/temporal thermometer) or (b) any influenza symptoms (cough, sore throat, nasal congestion, headache, feverishness or chills, muscle or joint pain, fatigue). * The time interval between the diagnosis of influenza and the pre-dose examinations is 48 hours or less. * For women of childbearing potential: Agreement to remain abstinent (refrain from heterosexual intercourse): * Women must remain abstinent or use contraceptive methods with a failure rate of \< 1% per year during the treatment period and for 28 days after the last dose of study treatment. Hormonal contraceptive methods must be supplemented by a barrier method. A woman is considered to be of childbearing potential if she is postmenarcheal, has not reached a postmenopausal state greater than or equal to 12 continuous months of amenorrhea with no identif…