Flu vaccine study in kids aims to find best dosing strategy

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * 3-8 years old; * The legal guardian / authorized agent gives the informed consent and voluntarily signs the informed consent to comply with the requirements of the clinical trial protocol; * Medical history, physical examination and clinical diagnosis, who to the immunization of this product. * children who have received two or more doses of influenza vaccine (4 weeks apart) before the season of this influenza epidemic (2 doses of influenza vaccine do not need to be vaccinated in the same epidemic season or consecutive epidemic season, but can be interpreted as children who have received two or more cumulative shots). History of l No immunization: children who had not been vaccinated or had previously received \<2 doses of influenza vaccine before the influenza season. Exclusion Criteria: 1.1.1The exclusion criteria for the first needle To l allergic to any component of the quadrialent influenza vaccine (history of any previous vaccine allergy), especially those allergic to eggs; The l axillary body temperature was 37.5℃ before inoculation; * Any influenza vaccine (registered or research) within 6 months prior to enrollment; or planned for use during the study period; * Use of immunoglobulin and / or any blood products within 3 months prior to enrollment; or planned for use during the study (before blood sampling); * Patients with a history of Guillain-Barre syndrome; l Acute disease, severe chronic disease, acute onset of chronic disease, cold; * Uncontrolled epilepsy; * Has been diagnosed with congenital or acquired immunodeficiency, HIV infection, lymphoma, leukemia, or other autoimmune diseases; * those receiving immune booster or inhibitor treatment within 3 months (continuous oral or drip for more than 14 days); * History of abnormal coagulation function (such as lack of coagulation factors, coagulation disease); * Primary and secondary impaired immunity (history of thyroid, pancreas, liver and spleen resection); * A history of severe allergic reactions to vaccination; * live attenuated vaccine within 14 days before vaccination and other vaccines within 7 days before vaccination; * Is in or recently planning to participate in other clinical trials; * Other conditions judged by the investigator as not suitable for participation in this clinical trial. 1.1.2 Exclusion criteria for the second needle * Patients with severe allergic reactions after the previous dose of vaccination; * Serious adverse reactions with a causal relationship with the previous dose of vaccination; l For newly detected or those who do not meet the inclusion criteria of the first injection or meet the exclusion criteria of the first injection, the investigator will determine whether to continue to participate in the study; * Other reasons for exclusion as considered by the investigator.