The purpose of this study is to evaluate safety and reactogenicity of live attenuated influenza H5 vaccine candidate strain A/17/turkey/Turkey/05/133 (H5N2) manufactured by GPO, in Thailand to previously healthy Thais.

It is a phase I randomized placebo controlled trial (vaccine and placebo ratio of 2:1). A phase II study is planned to be conducted following review of results of this phase.

Phase I: It is a double blind randomized placebo controlled trial involving 24 participants age 18-49 years (16 will receive vaccines and 8 will receive placebo). All will be admitted in the isolation ward for 10-14 days after each immunization mainly for safety assessment. Two doses of live attenuated influenza H5 vaccine candidate strain A/17/turkey/Turkey/05/133 (H5N2) will be given by intranasal route 21 days apart. Each group of 4 participants will be immunized at a time at 30-60 mins interval. All participants will be followed 21 days after each immunization. Total follow up is 60 day.

Inclusion Criteria:

• Healthy
• Age 18-49 years old
• Having Thai ID card or equivalent
• Are seronegative to the specific H5 influenza virus determined by antibody titer less than 1:40 by HAI test to the corresponding antigen.
• Anti HIV - Negative
• All hematology & biochemistry and urine analysis are within normal range or of no clinical significance (not more than 1.5 times of normal value)
• Able to read and write and sign written informed consent.

Exclusion Criteria:

• Known history of egg allergy
• Having had recently influenza infection confirmed as H5
• History of bronchial asthma
• History of chronic lung diseases
• History of chronic rhinitis
• History of immunodeficiency state
• History of immunosuppression
• History of heavy smoking (more than 5 rolls per day)
• History of alcoholic (pure drink 200 ml per day)
• 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 or stop participant less than 1 month
• Pregnancy or plan to become pregnant for 60 days after enrollment or breast feeding
• Any concomitant medication with Aspirin
• The volunteers who have family members with immunodeficiency
• Poultry workers
• Have undertaken international travel within the one week prior to immunization