The purpose of this study is to evaluate the safety and immunogenicity of quadrivalent influenza vaccine in healthy subjects aged over 3 years

This study is a phase I& III clinical trial. Phase I is open-labelled, and phase III is randomized, double-blind, active-controlled. The purpose of this study is to evaluate the safety and immunogenicity of the quadrivalent influenza vaccine (QIV) (experimental vaccine) manufactured by Sinovac Biotech Co., Ltd in subjects aged over 3 years. In phase I, 60 volunteers received single dose QIV (15µg/0.5ml). In phase III, 2320 volunteers were assigned to receive single dose QIV (15µg/0.5ml) or two commercial trivalent influenza vaccines (TIVs) (15µg/0.5ml) in a ratio of 2:1:1. The commercial TIVs were also manufactured by Sinovac Biotech Co., Ltd.

Inclusion Criteria:

• Healthy volunteers aged ≥3 years;
• Proven legal identity;
• Participants or (and) guardians of the participants should be capable of understanding the written consent form, and such form should be signed prior to enrolment;

Exclusion Criteria:

• Prior vaccination with influenza vaccine of the current year;
• History of influenza within 6 months prior to study entry;
• Axillary temperature > 37.0 °C;
• History of allergy to any vaccine, or any ingredient of the experimental vaccine, especially eggs, egg albumin, etc.;
• Serious adverse reaction(s) to vaccination, such as urticaria, dyspnea, angioneurotic edema, abdominal pain, etc.;
• Severe/uncontrollable nervous system disease (epilepsy, seizures or convulsions) or mental illness;
• Autoimmune disease or immunodeficiency/immunosuppressive, or any immunosuppressant receipt within 6 months prior to the study entry;
• History of asthma, thyroidectomy, angioedema, diabetes or malignancy;
• No spleen, or functional no spleen, or splenectomy.