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 the informed consent * Subjects themselves or their guardians can and will comply with the requirements of the protocol * Subjects have received ≥2 doses of trivalent or quadrivalent infuenza vaccine before enrollment (Doses need not have been received during same or consecutive seasons); Subjects have not received infuenza vaccine before enrollment * Subjects with temperature \<=37.0°C on axillary setting Exclusion Criteria: * Subject who has a medical or family history of any of the following: allergic history, seizure, epilepsy, brain or mental disease * Subject who is allergic to any ingredient of the vaccine * Subject with damaged or low immune function which has already been known * Subject with acute febrile illness or infectious disease * Major congenital defects or serious chronic illness, including perinatal brain damage * Thrombocytopenia, blood coagulation disorder or bleeding difficulties with intramuscular injection * Subject who has serious allergic history * Subject who developed guillain-Barre syndrome post influenza vaccination * Any prior administration of immunodepressant or corticosteroids in last 6 months * Any prior administration of influenza vaccine in last 6 month * Any prior administration of blood products in last 3 months * Any prior administration of other research medicine/vaccine in last 30 days * Any prior administration of any attenuated live vaccine in last 14 days * Any prior administration of subunit or inactivated vaccines in last 7 days, such as pneumococcal vaccine * Any medical, psychological, social or other condition judged by investigator, that may interfere subject's compliance with the protocol or signature on informed consent for subject's guardian