A Clinical Trial of an Inactivated Quadrivalent Influenza Vaccine in Chinese Children Aged 3 to 8 Years

Inclusion Criteria: * Aged 3-8 years old * Healthy subjects judged from medical history and clinical examination * Subjects themselves or their guardians able to understand and sign theinformed consent * Subjects themselves or their guardians can and will comply with therequirements of the protocol * Subjects have received ≥2 doses of trivalent or quadrivalent infuenzavaccine before enrollment (Doses need not have been received duringsame or consecutive seasons); Subjects have not received infuenzavaccine before enrollment * Subjects with temperature \<=37.0°C on axillary setting Exclusion Criteria: * Any prior administration of other research medicine/vaccine in last 30 days * Any prior administration of influenza vaccine in last 6 month * Any prior administration of immunodepressant or corticosteroids in last 3 months * Any prior administration of blood products in last 3 months * Any prior administration of any attenuated live vaccine in last 14 days * Any prior administration of subunit or inactivated vaccines in last 7 days * Subject who developed guillain-Barre syndrome post influenza vaccination * Subject who is allergic to any ingredient of the vaccine * Subject with acute febrile illness or infectious disease * Thrombocytopenia, blood coagulation disorder or bleeding difficulties withintramuscular injection * Subject with damaged or low immune function which has already beenknown * Subject with congenital heart disease or other birth defects unsuitable for vaccination. * Subject with respiratory diseases (including pneumonia, tuberculosis, severe asthma, etc.), heart, liver and kidney diseases, mental disorders, or chronic infections. * Any medical, psychological, social or other condition judged byinvestigator, that may interfere subject's compliance with the protocol