A Phase III Clinical Trial of Quadrivalent Influenza Vaccine in Healthy Subjects Aged 6 to 35 Months

Inclusion Criteria: * Healthy infants aged 6-35 months; * Proven vaccination certificate and birth certificate; * The subjects' guardians can understand and voluntarily sign the informed consent form. Exclusion Criteria: * Received any circulating seasonal influenza vaccine prior to enrollment or had an influenza vaccine schedule during the study; * Suffering from seasonal influenza in the past 6 moths; * Axillary temperature \>37.0°C; * History of allergy to the vaccine or vaccine components, or serious adverse reactions to the vaccine, such as urticaria, dyspnea, angioedema and asthma; * Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.; * Severe chronic diseases(Such as down syndrome, diabetes, sickle cell anaemia or neurological disorders); * Severe neurological disease (epilepsy, convulsions or convulsions) or mental illness; * Autoimmune disease (such as systemic lupus erythematosus) or immunodeficiency / immunosuppression (such as HIV, after organ transplantation) * Thyroid disease or history of thyroidectomy, asplenia,functional asplenia, asplenia or splenectomy resulting from any condition; * Diagnosed abnormal blood coagulation function (eg, lack of blood coagulation factors, blood coagulopathy, abnormal platelets) or obvious bruising or blood coagulation; * Continuous use of corticosteroids or other immunosuppressive agents for ≥ 14 days within the past 6 months (excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) and cytotoxic therapy in the past 6 months; * Acute diseases or acute exacerbation of chronic diseases in the past 3 days; * Receipt of blood products within in the past 3 months; * Receipt of other investigational drugs in the past 30 days; * Receipt of attenuated live vaccines in the past 14 days; * Receipt of inactivated or subunit vaccines in the past 7 days; * Participated in other clinical trials before enrollment and in the follow-up period, or plans to participate in other clinical trials during the clinical trial; * According to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial