This is a multicenter, single-arm, open-label study to assess the safety, pharmacokinetics, and efficacy of baloxavir marboxil in otherwise healthy pediatric patients from birth to <1 year with influenza-like symptoms.
Patients will be screened on Day 1 and assigned to one of three cohorts, based upon their age, to receive a single oral dose of baloxavir marboxil based on body weight and age. Re-screening of patients who fail to meet the inclusion and exclusion criteria will not be permitted, as the time from symptom onset to treatment window is limited to 96 hours.
The study consists of two periods: a 1-day treatment period (screening and study drug administration on Day 1) and a 28-day safety follow-up period (mandatory visits on Days 2, 4, 6, 10, and 29). Therefore, the total study duration for each patient will be 29 days.