Phase III Clinical Trial of Quadrivalent Influenza Virus Split Vaccine

Inclusion Criteria: * Age Requirement: volunteers aged 3 years and above at the time of enrollment. * Provision of Legal Identification: Volunteers and their legal guardians or appointed representatives must provide valid legal identification documents. * Informed Consent: Volutters, legal guardians, or appointed representatives of volunteers must have the capacity to understand the informed consent document and the research process, voluntarily participate, sign the informed consent form, and be able to comply with the requirements in the study as well as complete relevant visits on time. * Requirements for contraception: agree to take contraception actions in 6 months. * Temperature Requirement: Axillary body temperature is less than 37.3°C. * Previous Vaccination Requirements: (a) Received at least 1 dose of influenza vaccine within 1 year before screening in children aged 3-8 years; (b) Never received any influenza vaccine 1 year before screening in children aged over 3 years. Exclusion Criteria: Subjects meeting any of the following exclusion criteria will be not eligible for enrollment. * Subjects with a history of severe allergy to egg or egg protein, such as those who have had symptoms such as angioedema, dyspnea, chest distress, or repeated vomiting due to eating eggs, and even those who have used epinephrine or other emergency medical treatment, especially those who have symptoms immediately or within a short period (minutes to hours). * Subjects with influenza illness (clinically, serologically, or microbiologically confirmed) within 6 months before screening and enrollment. * Have received an influenza vaccine within 1 year before enrollment or scheduled to receive another influenza vaccine during the study period. * Allergic to any component contained in the investigational vaccine, or previous history of severe allergic to any vaccine or drug, such as anaphylactic shock, laryngeal edema, anaphylactic purpura, thrombocytopenic purpura, local allergic necrosis reaction, dyspnea, angioedema, systemic rash and/or urticaria, etc. * History of taking administration of a non-SARS-CoV-2 inactivated vaccine or subunit vaccine within 7 days before enrollment, or any live attenuated vaccine or SARS-CoV-2 vaccine within 14 days before enrollment, or subjects have scheduled to receive another vaccine within 1 month after receipt of the investigational vaccine * Subjects with convulsion, epilepsy, encephalopathy (such as moderate to severe hypoxic-ischemic encephalopathy, intracranial hemorrhage, cerebral palsy, intracranial tumor, cerebral infarction, stroke, intracranial infection, etc.), psychiatric history or family history * Have been diagnosed with a serious medical condition or congenital malformation that may interfere with the conduct or completion of the study (including but not limited to suffering from respiratory diseases such as asthma or during episodes of chronic bronchitis, Down syndrome, thalassemia, heart disease, severe cardiac arrhythmias, kidney disease, diabetes (diabetics with poor glycemic control or severe complications), autoimmune diseases, genetic allergies, Guillain-Barre syndrome, Crohn disease, malignancies, severe infectious/allergic skin diseases, etc.) * Adults aged 18 years or older with medically uncontrolled abnormal blood pressure (systolic blood pressure ≥140mmHg and/or diastolic blood pressure ≥90mmHg or systolic blood pressure ≤ 90mmHg and/or diastolic blood pressure ≤ 60 mmHg) * Subjects with acute illness or in the acute phase of a chronic illness within 3 days before vaccination * Subjects with fever (axillary temperature ≥37.3 ° C) within 3 days before vaccination or use of antipyretic, analgesic, or antiallergic medications * Subjects with a hereditary bleeding tendency or coagulopathy, or a history of bleeding disorders * Have received a blood transfusion or use of blood products within 3 months before enrollment, or planned to do so within 1 month after full immunization * History of surgical removal of the spleen or other vital organs for any reason * Use of any investigational or unregistered product (drug, vaccine, biological product, or device) other than a study vaccine within 3 months before enrollment or planned for use during the study * Have treatment with immunosuppressive agents within 6 months before enrollment, such as long-term systemic glucocorticoid therapy (e.g., prednisone or a similar drug for more than 2 consecutive weeks within 6 months), but topical use (e.g., ointments, eye drops, inhalers, or nasal sprays) was allowed. Topical use should not exceed the recommended dose on the label or have any signs of systemic exposure * Have been diagnosed with an infectious disease that may interfere with the conduct or completion of the study, such as active tuberculosis, hepatitis B, hepatitis C, human immunodeficiency virus (HIV) infection, etc * Being lactating, pregnant (including a positive urine pregnancy test), or planning to become pregnant within 6 months of vaccination * Subjects plan to move out of the local area before the end of the study or leave the local area for an extended period during the scheduled study visit * Subjects with abnormal vital signs with clinical significance * Investigators' Discretion: The final exclusion criterion is the discretion of investigators to determine whether a subject is suitable for participation in the study.