Study of the Safety, Tolerability and Immunogenicity of an Intranasal Influenza Vaccine Administered to Healthy Adults

Inclusion Criteria: 1. Non-smoking adult aged between 20-40 years old; 2. Physically and mentally healthy subjects as confirmed by an interview, medical history, clinical examination, chest X-rays, ophthalmoscopy, cardiac echo, and electrocardiogram; 3. Body Mass Index (BMI) between 18.5 and 25, inclusive, (BMI will be calculated as weight in kilogram \[kg\]/height in meters2 \[m2\]); 4. Normal hematology, biochemistry and urinalysis determinations; 5. Subject is willing and able to comply with study procedures and sign informed consent Exclusion Criteria: 1. Subject with serious underlying chronic illness; 2. Documented evidence of allergic rhinitis; 3. Subject with acute sinusitis or chronic sinusitis accompanying acute symptoms within 3 days prior to enrollment; 4. Immunosuppressed subjects as result of illness or treatment; 5. Female subject of childbearing potential who: * is lactating; or * has positive urine pregnancy test at Visit 2 or Visit 3; or * refuse to adopt reliable method of contraception during the study; 6. Subject received blood products or immunoglobulin within 3 months prior enrollment; 7. Subjects with long-term use of steroids, including parenteral steroids or high dose inhaled steroids within 28 days prior to enrollment; 8. Subject has received any intranasal medication or nasal topical treatment within 7 days prior to enrollment; 9. Subject has received any investigational agent within 28 days or 5 half- lives, whichever is longer, prior to the first dose of investigational product; 10. Subject has previously experienced anaphylaxis; 11. Subject has allergy to eggs or prior influenza vaccine; 12. Subject with laboratory-confirmed influenza or has been vaccinated against influenza within 6 months prior to enrollment; 13. Subject with acute respiratory illness or administered antibiotics or antivirals within 7 days prior to enrollment; 14. Subject with body temperature high than 38°C within 3 days prior to enrollment; 15. Subject with documented history of Bell's palsy or neurological disorder. 16. Subject with documented history of diarrhea within one month prior to study enrollment 17. A positive test for HIV antibody. 18. Subject has received Chinese medication or herbal medication within 28 days prior to enrollment