Efficacy and Safety of ZSP1273 in Children 12-17 Years Old With Influenza A

• ZSP1273 (Drug): Oral
• Placebo (Drug): Oral

Primary outcomes

• Time to Alleviation of Symptoms [DAY1~DAY15]: Participants assessed the severity of seven influenza-associated symptoms (cough, sore throat, headache, nasal congestion, feverishness or chills, muscle or joint pain, and fatigue) on a 4-point scale (with 0 indicating no symptoms, 1 mild symptoms, 2 moderate symptoms, and 3 severe symptoms).

Secondary outcomes

• Number of participants with treatment-related adverse events as assessed by CTCAE v5.0 [DAY1~DAY15]
• Plasma concentrations of ZSP1273 [DAY1~DAY15]

Sex: All, ages: 12 Years to 17 Years

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.