Suraxavir Marboxil And Oseltamivir for Influenza Prophylaxis Under a Hospital-based Setting

1.Inclusion Criteria: (1)Inclusion Criteria for Index Cases: ① Patients hospitalized at a participating medical institution. * The subject and/or their legal guardian agrees to participate in this clinical study, has signed the informed consent form, and is able to comply with the protocol requirements for follow-up and complete all study procedures and assessments. * Age ≥ 2 years. * Positive for influenza virus as determined by a Rapid Antigen Test (RAT) or Nucleic Acid Amplification Test (NAAT) on a respiratory specimen (e.g., oropharyngeal swab, nasopharyngeal swab, sputum, or bronchoalveolar lavage fluid). (2) Inclusion Criteria for Room Contacts: ① Patients hospitalized at a participating medical institution. * The subject and/or their legal guardian agrees to participate in this clinical study, has signed the informed consent form, and is able to comply with the protocol requirements for follow-up and complete all study procedures and assessments. ③ Age ≥ 12 years. * Expected to remain hospitalized for ≥ 72 hours. * Shares a room with at least one hospitalized index case who has been confirmed with influenza virus infection by RAT or NAAT on a respiratory specimen within the last 120 hours and developed influenza-related symptoms within the last 120 hours, and is expected to share the same room for ≥ 24 hours. ⑥ Negative for influenza virus as determined by a Nucleic Acid Amplification Test (NAAT) on a throat swab collected on …