Exploration on the Quadrivalent Influenza Vaccine Immunization Schedule for Children Aged 3-8 Years
Condition: GCP
Study type: Observational

Summary: 
      The goal of this [To evaluate the immunogenicity and safety of 1 - and 2-dose schedules of
      quadrivalent influenza vaccine (split virion) in healthy people with and without immunization
      history.] is to [aged 3-8 years] in [Healthy people]. The main question[s] it aims to answer
      are: • [To evaluate the immunogenicity of a two-dose schedule of quadrivalent influenza
      vaccine (quadrivalent influenza vaccine) in healthy population aged 3-8 years with or without
      vaccination history.]

      •[ To evaluate whether antibody levels are different 30 days after one dose of quadrivalent
      influenza vaccine versus two doses of quadrivalent influenza vaccine in healthy people aged
      3-8 years with or without vaccination history.]
    

Detailed description: 
      An open clinical trial design was used. A total of 652 healthy children aged 3-8 years, 326
      with vaccination history and 326 without vaccination history, were selected to receive two
      doses of normal commercially available quadrivalent influenza vaccine according to a 0 -,
      30-day schedule.

      Immunogenicity: blood samples were collected for HI antibody detection before the first dose
      of influenza vaccine (before immunization), 30 days after the first dose of influenza vaccine
      (before the second dose of influenza vaccine) and 30 days after the second dose of influenza
      vaccine.

      Adverse events (AE) were observed 30 minutes, 0-7 days and 8-30 days after each dose of
      vaccination by active follow-up combined with guardian reports. Occurrence of SAEs between 31
      and 180 days after the second dose of vaccine.

      Criteria for evaluation of immunogenicity 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.
    

Intervention name(s): Influenza Vaccine (Split Virion), Inactivated, Quadrivalent
Intervention type(s): Biological
Intervention description(s): A total of 652326 healthy children with immunization history and no immunization history aged 3-8 years who met the program requirements received two doses of normally commercially available quadrivalent influenza vaccine according to the 0,30-day procedure.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Healthy people aged 3-8 years old
      
Biospecimen description: 
      Approximately 3ml of blood was collected on day 0, day 30 (before the second dose of
      inoculation), and day 60