This trial is conducted in China. This is a multi-center, randomized, double-blind, placebo-controlled clinical trial to assess the efficacy and safety of ZSP1273 in the treatment of Acute Uncomplicated influenza A in adolescents.

Inclusion Criteria:

1. Participants 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 participants aged ≥ 2 to ≤11 years at the time of signing the informed consent form.

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

   1. Positive rapid antigen test (RAT) for influenza with nasal or throat swabs;
   2. The time interval between the onset of symptoms and enrollment is 48 hours or less;
   3. Fever ≥ 38ºC (axillary temperature); and at least one following respiratory symptoms associated with influenza virus infection is present

Exclusion Criteria:

1. Participants with severe influenza virus infection；
2. Participants 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. Participants with concurrent infections requiring antimicrobial therapy；
7. Participants who are considered inappropriate for the study by the investigator.