To evaluate the inter-batch consistency (CI) of quadrivalent influenza vaccine (split virion) among healthy people aged 18-59 years； Secondly, to evaluate the safety and immunogenicity of quadrivalent influenza vaccine (split virion) in the expanded population aged 3 years and above, in order to observe the rare adverse reaction of 1‰.

The study was divided into two parts. The first part was an inter-batch consistency study (a randomized, double-blind, 1050 subjects aged 18-59 years). The second part was the safety and immunogenicity study in the expanded population aged 3 years and above (enrollment 4900).were selected to receive of normal commercially available quadrivalent influenza vaccine。 Safety observation: follow-up was conducted to observe the occurrence of AE within 30 minutes (0 day) and 0-30 days after vaccination, and the occurrence of SAE within 6 months after vaccination.

Immunogenicity observation: Blood samples were collected from all subjects before and 30 days after vaccination for influenza virus HI antibody detection。 According to the European Union seasonal influenza evaluation criteria, if the HI antibody seroconversion rate of each subtype of influenza virus was ≥40%, the HI antibody positive rate was ≥70%, and the GMI of each subtype of influenza virus was ≥2.5 times 30 days after any dose of vaccination, the vaccination schedule was considered to have acceptable immunogenicity.

Safety outcome MEASURES The occurrence of adverse reactions/events after each dose of vaccination was observed. The incidence of ① total adverse reactions/events, ② incidence of grade 3 or above adverse reactions/events and SAE, ③ incidence of adverse reactions/events severity classification, ④ incidence of adverse reactions/events by type (inoculation site and systemic, SOC, PT) and incidence of adverse reactions/events severity classification were calculated.

Note: Known adverse effects of quadrivalent influenza vaccine that have been identified in previous clinical studies are as follows:

Inoculation site (local) adverse events: pain, induration, swelling, rash, redness, pruritus, cellulitis.

Adverse events at non-inoculated sites (systemic) included fever, diarrhea, constipation, dysphagia, anorexia, vomiting, nausea, myalgia (non-inoculated sites), arthralgia, headache, cough, dyspnea, pruritus at non-inoculated sites (without skin lesions), mucocutaneous abnormalities, irritation/inhibition, acute anaphylaxis, and fatigue/fatigue.

Inclusion Criteria:

• Healthy people aged 3 years and above;
• I (or/and his/her legal guardian/authorized representative) can comply with the requirements of the clinical trial protocol after informed consent and voluntary signed informed consent;
• No contraindications of quadrivalent influenza vaccine in the package insert and meet the vaccination requirements after medical history inquiry.

Exclusion Criteria:

• Allergy to any component of the quadrivalent influenza vaccine, including egg, excipients, formaldehyde, or Triton X-100;
• people with a history of anaphylaxis after vaccination (allergy to any previous vaccination);
• Acute disease, severe chronic disease, acute onset of chronic disease, cold and fever;
• Axillary body temperature ≥37.3℃ (> 14 years old) and ≥37.5℃ (≤14 years old) before vaccination;
• Uncontrolled epilepsy;
• patients with progressive neurological disease or a history of Guillain-Barre syndrome;
• receiving immunoglobulin injection for less than one month;
• vaccination with live attenuated vaccine within 14 days before and other vaccines within 7 days before vaccination;

Healthy people aged 3 years and older