Study to Assess the Safety, Pharmacokinetics, and Efficacy of Baloxavir Marboxil in Healthy Pediatric Participants With Influenza-Like Symptoms

A Multicenter, Randomized, Double-Blind, Active (Oseltamivir)-Controlled Study to Assess the Safety, Pharmacokinetics, and Efficacy of Baloxavir Marboxil in Otherwise Healthy Pediatric Patients 1 to <12 Years of Age With Influenza-Like Symptoms

This study will evaluate the safety, pharmacokinetics, and efficacy of baloxavir marboxil compared with oseltamivir in a single influenza episode in otherwise healthy pediatric participants (i.e., 1 to <12 years of age) with influenza-like symptoms.

Inclusion Criteria:

• Aged 1 to < 12 years at randomization (Day 1).
• Written informed consent/assent for study participation obtained from participant's parents or legal guardian, with assent as appropriate by the participant, depending on the patient's level of understanding
• Participant able to comply with study requirements, depending on the patient's level of understanding
• Participant with a diagnosis of influenza virus infection confirmed by the presence of all of the following:
• Fever ≥ 38 degree celsius (tympanic temperature) at screening
• At least one respiratory symptom (either cough or nasal congestion)
• The time interval between the onset of symptoms and screening is ≤ 48 hours

Exclusion Criteria:

• Severe symptoms of influenza virus infection requiring inpatient treatment
• Concurrent infections requiring systemic antiviral therapy at screening
• Require, in the opinion of the investigator, any of the prohibited medication during the study
• Previous treatment with peramivir, laninamivir, oseltamivir, zanamivir, or amantadine within 2 weeks prior to screening
• Immunization with a live/attenuated influenza vaccine in the 2 weeks prior to randomization
• Concomitant treatment with steroids or other immuno-suppressant therapy
• Known HIV infection or other immunosuppressive disorder
• Uncontrolled renal, vascular, neurologic, or metabolic disease (e.g., diabetes, thyroid disorders, adrenal disease), hepatitis, cirrhosis, or pulmonary disease or participants with known chronic renal failure.
• Active cancer at any site
• History of organ transplantation
• Known allergy to either study drug (i.e., baloxavir marboxil and oseltamivir) or to acetaminophen
• Females with child-bearing potential
• Participation in a clinical trial within 4 weeks or five half-lives of exposure to an investigational drug prior to screening, whichever is longer