A Phase II, Randomized, Double-blind, Placebo-controlled Study to Examine the Effects of DAS181 in Immunocompromised Subjects With Lower Respiratory Tract Parainfluenza Infection on Supplemental Oxygen

Inclusion Criteria: * Age ≥12 years * Able to provide informed consent, child assent with parental consent or surrogate consent when applicable * Currently on invasive mechanical ventilation or noninvasive positive pressure ventilation (CPAP or bilevel positive airway pressure) or requiring \> 2LPM supplemental oxygen therapy to maintain O2 saturation \> 90% due to hypoxemia * Immunocompromised, as defined by one of the following: Autologous or Allogeneic hematopoietic cell transplantation (HSCT); Lung or lung-heart transplantation; Subjects treated with chemotherapy for hematologic malignancies; Subjects treated with chemotherapy for solid tumor malignancies * Confirmed parainfluenza at screening by one of the following methods using any sample type: Respiratory Virus Panel, Direct fluorescent antibody (DFA), Qualitative/quantitative RT-PCR test for parainfluenza virus performed at the local laboratory (a confirmatory PCR test will be done at the central lab but is not required to start the patient on study). * Confirmed PIV lower tract disease for subjects on mechanical ventilation will be defined as PIV detection in bronchoalveolar lavage (BAL) or biopsy within last 7 days of screening * Confirmed PIV lower tract disease for subjects on non-invasive positive pressure ventilation or supplemental oxygen will be defined as all of the following within the last 7 days of screening: New pulmonary infiltrate on chest imaging and at least one PIV sign and/or symptom as defined in…