Phase IIIb Study of Baloxavir Marboxil Treatment in Children With Influenza and Flu Spread to Household Members

What this Trial Is About

Researchers are studying influenza in children younger than 12 years to understand how the virus changes when treated with the drug baloxavir marboxil. This study has two parts Part A monitors the presence and development of specific changes in the virus before and after treatment in pediatric patients. Part B focuses on how influenza spreads within households from treated children under 12 to their family members, though no new participants will join Part B as per the latest study update. Participants receive a single oral dose of baloxavir marboxil on the first day, with the dose based on their body weight and age. Household contacts of the treated children are enrolled for observation but do not receive the drug. The study tracks viral changes and resistance at multiple points, including baseline and several days after treatment, and monitors influenza transmission within households. Throughout the study, children will undergo various tests such as local influenza and SARS-CoV-2 testing to confirm infection status. Researchers will measure how often virus mutations associated with resistance occur, changes in viral levels, and any side effects up to 29 days. For household contacts, influenza transmission and symptom development are checked on days 6 and 10. Participation involves scheduled visits and testing to gather this information, with the study expected to continue until mid-2027.

A Surveillance Study of Susceptibility to Baloxavir Marboxil in Pediatric Participants With Influenza and Transmission of Influenza to Household Contacts