A Surveillance Study of Susceptibility to Baloxavir Marboxil in Pediatric Participants With Influenza and Transmission of Influenza to Household Contacts
This study consists of two parts: Part A Surveillance and Part B Transmission.
The main purpose of Part A is to evaluate the prevalence of pre-dose and treatment-emergent amino acid substitutions in pediatric participants' \<12 years with influenza treated with baloxavir marboxil.
Part B will include a subset of Part A participants who have household contacts (HHCs) recruited to the study. Part B will evaluate the incidence of onward influenza transmission from pediatric index participants (IPs) under 5 years of age and those aged 5 to under 12 years, treated with baloxavir marboxil, to their HHCs. Participants will no longer be enrolled to Part B Transmission as per protocol version 3.