Totally 160 health people aged 3-59 years old will be divided into two age group, containing 80 in 18-59 years old and 80 in 3-19 years old. All subjects will receive vaccination either LAVI or placebo in a ratio of 3:1.~All subjects will be collected any adverse events within 30 days and any serious adverse events within 6 months for safety evaluation.~All subjects will be collected blood sample and nasopharyngeal swab for immunogenicity evaluation.
Live Attenuated freeze-dried Influenza Vaccine has been licensed for use in 2020 (Approval No.S20200002), the sponsor of this research submitted an new application for non freeze-dried Live Attenuated Influenza Vaccine in 2021. The main objective of phase Ⅰ trail is to evaluate the safety of LAVI(non freeze-dried). The secondary objective is to evaluate the immunogenicity of LAVI(non freeze-dried).