Study to Assess the Safety, Pharmacokinetics, and Efficacy of Baloxavir Marboxil in Chinese Pediatric Participants 1 to <12 Years of Age With Influenza Symptoms

A Phase III, Randomized, Open-Label, Active-Controlled Study to Assess the Safety, Pharmacokinetics, and Efficacy of Baloxavir Marboxil in Chinese Pediatric Patients 1 to <12 Years of Age With Influenza Symptoms

The purpose of this study is to evaluate the safety of a single dose baloxavir marboxil compared with 5 days of oseltamivir administered twice a day (BID) in Chinese pediatric participants aged 1 to < 12 years with influenza symptoms.

Inclusion Criteria:

• A participant who has a diagnosis of influenza virus infection and meets all the following conditions:

  • Fever ≥ 38°C (tympanic temperature) at screening
  • At least one of the respiratory symptoms of influenza virus infection

• A rapid influenza diagnostic test (RIDT) or polymerase chain reaction (PCR) shows positive for influenza A/B, e.g., point-of-care/local laboratory results with use of nasal aspirate, throat swab, or nasal drip/droplet (or other appropriate sample)

• The time interval between the onset of symptoms and screening is ≤ 48 hours

• PCR (-) or antigen test (-) for severe acute respiratory virus-coronavirus 2 (SARS-CoV-2) using point-of-care/local laboratory test with nasal aspirate, throat swab, or nasal drip/droplet (or other appropriate sample)

Exclusion Criteria:

• A participant having severe influenza virus infection symptoms requiring inpatient treatment
• Received systemic corticosteroid or immunosuppressive therapy
• Primary immunodeficiency syndrome
• History of organ transplantation
• Human immunodeficiency virus (HIV) infection
• Immunization with a live/attenuated influenza vaccine in 2 weeks prior to randomization
• Previous malignancy within the last 5 years or has an active cancer at any site
• A participant who received any medications with anti-flu effect such as baloxavir, peramivir, oseltamivir, zanamivir, favipiravir, arbidol, amantadine or traditional Chinese anti-influenza medicines within 30 days before screening
• Diagnosed with or suspected SARS-CoV-2 infection, or close contacts of diagnosed or suspected SARS-CoV-2 infected patients
• Severe underlying disease or condition potentially affecting study evaluation in the opinion of the investigator/sub-investigator
• A participant who received an investigational or unapproved drug product within 30 days or 5 x the half-life before screening, whichever is longer