Phase III Clinical Study Evaluating the Safety, Pharmacokinetics, and Efficacy of JKN2301 Dry Suspension in Pediatric Patients Aged 2 to Under 12 Years With Influenza

• JKN2301 Dry Suspension (Drug): Single oral dose, administered according to a weight-tiered dosing scheme.
• Oseltamivir Placebo (Drug): Oral suspension, administered twice daily for 5 days, matched to the weight-based dosing of active oseltamivir.
• Oseltamivir (Drug): Oral suspension, administered twice daily for 5 days according to the approved weight-based dosing regimen.
• JKN2301 Placebo (Drug): Single oral dose, matched to the weight-tiered dosing scheme of active JKN2301.

Primary outcomes

• Incidence, severity, and relationship to treatment of adverse events (AEs) and serious adverse events (SAEs) [Baseline through Day 15]
• Clinically significant changes in laboratory parameters, vital signs, physical examination, and ECG [Baseline through Day 15]

Secondary outcomes

• Plasma concentration-time profiles of JKN2301 and its relevant metabolites [At multiple timepoints up to Day 6]
• Time to alleviation of all influenza symptoms [From treatment initiation up to Day 15]
• Duration of fever [From treatment initiation up to Day 15]
• Time to cessation of viral shedding assessed by viral culture [From treatment initiation up to Day 9]
• Change from baseline in viral titer [Baseline to Day 9]
• Incidence of influenza-related complications [Up to Day 15]

Sex: All, ages: 2 Years to 11 Years

Inclusion Criteria:

* Pediatric patients within the specified age range.
* Clinical presentation consistent with influenza, confirmed by a positive local rapid test or central laboratory PCR test.
* Presentation for treatment within the early symptomatic phase of influenza illness.
* Presence of fever and at least one respiratory symptom.
* Ability to swallow oral suspension.
* Parent/guardian and patient (as age-appropriate) able to provide informed consent/assent.

Exclusion Criteria:

* Clinical signs suggestive of severe or complicated influenza infection
* requiring inpatient management.
* Presence of a concurrent bacterial infection requiring systemic therapy.
* Significant immunocompromised, or severe/uncontrolled comorbid conditions.
* History of hypersensitivity to any component of the investigational products.
* Use of prohibited medications (including other anti-influenza antivirals) within a specified period prior to enrollment.
* Recent participation in another interventional clinical trial.
* Any condition that, in the opinion of the investigator, would jeopardize patient safety or compliance with the study protocol.