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).

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.

Inclusion Criteria:

• Healthy volunteers aged in 3-59 years old.
• Had not received vaccination of Influenza vaccine in the past half of years.
• Had not infected with Influenza virus.
• This trail has been agreed by volunteers or his/her legal guardian.
• Volunteers or his/her legal guardian will fellow this trail protocol.

Exclusion Criteria:

• People from 18-59 age group with abnormal laboratory index. (slight abnormality is except if judged with no clinical significance by doctors.)
• People with fever before vaccination, temperature higher than 37.0 ℃
• Females in suckling period, pregnancy (pregnancy test positive) or prepared to be pregnant
• People given whole blood, plasma or immunoglobulin therapy within 3 months before vaccination
• According to judgement of researchers, the subjects have any other factors that are not appropriate for this clinical trials.
• Acute infectious disease or acute attack of chronic disease before inoculation
• People get any vaccine within 14 days before the trial.
• People in immune deficiency or diagnosed with congenital or acquired immunodeficiency, people with immunosuppressive therapy in the past six months.
• People with epilepsy or a history of mental illness

The design of this trail is based on random, two-blind, placebo control. The subjects and investigators will not know the masking status, unless the specific subjects who required treatment for serious adverse events .