Critères d'inclusion : 1. Has undergone autologous or allogeneic HCT using any conditioning regimen within 1 year of randomization. Subjects who have undergone HCT more than 1 year before Randomization are eligible if all other inclusion/exclusion criteria are satisfied and under at least one of the following conditions:
a Diagnosed with Chronic Graft-vs-Host Disease (GVHD), or
b Has used systemic corticosteroids in the 30 days prior to RSV infection
2. Has moderate to severe immunocompromise, defined as a score ≥ 5 on the ISI-RSV and/or an ALC of ≤ 500 cells/ mm3
3. Documentation of positive RSV infection in the upper airway
Critères de non-inclusion : 1. Use of non-marketed investigational agents within 30 days, OR use of an
investigational monoclonal anti-RSV antibodies within 4 months or 5 half-lives of screening, whichever is longer, OR use of any investigational RSV vaccines after HCT.
2. Receiving a prescription, OTC, or herbal medication that is a potent inducer or inhibitor of CYP3A4, within 2 weeks of Randomization.
3. Receiving a prescription, OTC, or herbal medication that is a substrate of CYP3A4 with a narrow therapeutic index where monitoring blood levels is not possible.
4. Known chronic infection with hepatitis B, C, or HIV.
5. Is in the pre-engraftment period during RSV infection.
6. Admitted to the hospital primarily for lower respiratory tract disease of any cause as determined by the Investigator.
7. Any condition requiring mechanical ventilation or vasopressor support at the time of randomization.
8. Clinically significant bacteremia or fungemia within 5 days prior to Screening that has not been adequately treated.
9. Clinically significant bacterial, fungal, or viral pneumonia within 2 weeks prior to Screening that has not been adequately treated.
10. Excessive nausea/vomiting at Screening or an inability to swallow capsules.
11. Elevation of hepatic enzymes or renal compromise.