We switched this study design to another study per IEC's recommendations.

This study will assess the safety, tolerability, pharmacokinetics (PK) and anti-viral effect of single dose of AK0529 in infants hospitalized with respiratory syncytial virus (RSV).

This is a open-label Phase 1b study to evaluate the safety, tolerability, pharmacodynamics and Pharmacokinetics of AK0529 in hospitalized RSV infected infants age from 1 to 24 months.

Inclusion Criteria:

• Male or female subjects of any race or ethnicity with an age adjusted for any prematurity of ≥1 month and ≤24 months.
• Diagnosis of RSV infection by virological.
• Subject must weigh >3 kg at screening.
• Must have provided written informed consent for the subject to participate.
• For patients aged <12 months, and occipitofrontal head circumference (OFHC) within the normal range for age and gender.

Exclusion Criteria:

• The subject has taken, is currently taking or requires any restricted medications.
• Subject is known to be HIV-positive (or the mother, if the potential subject is a child aged <6 months).
• Participation in an investigational drug or device study within 30 days prior to the date of screening.
• Requires vasopressors or inotropic support at the time of enrollment.
• Concurrent gastrointestinal conditions that could, in the opinion of the investigator, prejudice absorption of the Investigational Medicinal Product (e.g. protracted vomiting, malabsorption syndrome, a history of necrotising enterocolitis with consequent short gut syndrome).
• Bronchopulmonary dysplasia or chronic lung disease requiring assisted ventilation at the time of enrollment.
• Diminished ventilatory reserve at risk for hypercapnia (e.g. pulmonary hypoplasia, sequestration syndromes, cystadenomatoid malformation, a history of surgery for diaphragmatic hernia).
• Left to right shunt meriting corrective therapy.