Clinical Trial of the Inactivated Influenza Vaccine (0.25ml Formulation for Pediatric Use)

Inclusion Criteria: * Infants aging 6-36 months, their guardians understand and sign the informed consent * Healthy infant by inquiring illness history, physical examination and clinical judgment and who complies with vaccination of this product * Be able to comply with the requirement of clinical trial protocol * Have no history of vaccination within the past 6 months and vaccination with other product within the latest 1 week * Axillary temperature ≤37.0℃. Exclusion Criteria: 1. Exclusion criteria for primary vaccination: * History of other vaccine or immunoglobulin inoculation within 2 weeks * History of eclampsia, epilepsy, encephalopathy and mental disease or family disease * History of vaccination allergy or allergy to drug and food (egg) * Known or suspected immunological function defects, including immunosuppressant therapy (radiotherapy, chemotherapy, corticosteroid hormone, antimetabolites, cytotoxic drug), genetic defects (favism), HIV infection or other reasons * Congenital malformation, maldevelopment or serious chronic disease (such as Down syndrome, diabetes, sickle cell anemia or neurologic disease) * Acute and chronic contagion, active infection (history of fever within the past 3 days (axillary temperature ≥38.0℃) or acute disease needing application of antibiotics or anti-virus treatment in the whole body) * Organic diseases such as liver, kidney, serious cardiovascular disease * Malignancy (tumor), serious asthma * Thrombopenia or other coagulopathy that may cause contraindication of intramuscular injection * Any condition resulting in the absence or removal the spleen * Hypertension (not including the higher blood pressure below 150mmHg and lower blood pressure below 100mmHg controlled by drug) * Participating in another clinical trial or any condition that, in the judgment of investigator, may affect trial assessment. 2. Exclusion criteria for a boost vaccination: * Any condition in the "Exclusion criteria" of the first injection after inclusion * Adverse reactions level 3 or above within 72 hours after first vaccination; * Serious adverse reactions having casual relationship with the first inoculation of test vaccine * Subjects are not willing to be inoculated any more and quit * Axillary temperature ≥37℃ before immunization * Reasons that can not conduct inoculation, in the judgment of investigators.