This trial is conducted in China. The aim of the trial is to investigate safety,pharmacokinetics and pharmacodynamics of ZSP1273 granules

Inclusion Criteria:

1. Subjects and their guardians who are able to understand the study and comply with all study procedures, and willing to provide written informed consent/assent prior to the predose examinations appropriately.

2. Male or female subjects aged ≥ 2 to ≤17 years at the time of signing the informed consent form.

3. Subjects with a diagnosis of influenza virus infection confirmed by all of the following:

   • Positive rapid antigen test (RAT) for influenza with nasal or throat swabs;
   • The time interval between the onset of symptoms and enrollment is 72 hours or less;
   • Fever ≥ 38ºC (axillary temperature); and at least one following respiratory symptoms associated with influenza virus infection is present

Exclusion Criteria:

1. Subjects with severe influenza virus infection；
2. Subjects with any medical history in gastrointestinal that interferes with the absorption of drugs；
3. Immunodeficiency,including malignant tumor,organ or marrow transplant,human immunodeficiency virus [HIV] infection,or patients receiving immunosuppressant therapy 3 months prior to enrollment；
4. Have received any other investigational products within 3 months prior to dosing；
5. Positive urine pregnancy test；
6. Subjects with concurrent infections requiring antimicrobial therapy；
7. Subjects who are considered inappropriate for the study by the investigator.