Phase I/II Safety and Immunogenicity of Pandemic Live Attenuated Influenza Vaccine (PLAIV) Candidate Strain A/17/CA/2009/38 (H1N1) in Healthy Thais

Part A: 24 volunteers will be enrolled and divided into 2 groups -12 volunteers in each of 2 groups receiving either 5.0-6.5 log 10 EID50 or 6.6-7.5 log10 EID50 respectively. 9 who will received vaccine vaccine strain and 3 who will received placebo.

Part B: Total 324 participants will randomized into 2 group using 3:1 ratio (300 vaccines:100 placebos). There are 3 stratified age groups: >12-18 years, >18-49 years and >49 years.

Inclusion criteria

• Healthy
• Age 9 - >49 years old
• Having Thai ID card or equivalent
• Are seronegative to the specific H1N1 influenza virus determined by antibody titer less than 1:10 by HAI test to the corresponding antigen
• Anti HIV - Negative
• All hematology & biochemistry within normal range
• Able to read and write and sign written informed consent

Exclusion criteria

• Known history of egg allergy
• Having had recently influenza infection confirmed as H1N1 (indeed all other types if Influenza and vaccination with seasonal vaccine will not interfere)
• History of bronchial asthma
• History of chronic lung diseases
• History of chronic rhinitis
• History of immunodeficiency state
• History of immunosuppression
• Acute infectious and noninfectious diseases (within 2 weeks)
• Exacerbation of chronic diseases or cancer or HIV positives
• Anamnestic leukocytosis, hepatitis B and C positives
• The volunteers who have been taking immunoglobulin products or have had a blood transfusion during past three months before the beginning of the experiment
• Participation in other research study
• Pregnancy or plan to become pregnant for 60 days after enrollment or breast feeding
• Any concomitant medication with Aspirin