Influenza Immunity Against Pandemic Respiratory Virus

Inclusion Criteria: Healthy adult, aged 18-49 years who have or have not participated in the Year 1 protocol. Willing to sign informed consent. Availability for follow-up for the planned duration of the study at least 4 weeks after immunization. Acceptable medical history by screening evaluation and brief clinical assessment. Negative urine or serum pregnancy test for women of childbearing potential. If the subject is female and of childbearing potential, she must use an acceptable contraception and not become pregnant for the duration of the study. (Acceptable contraception includes implants, injectables, combined oral contraceptives, effective intrauterine devices (IUDs), sexual abstinence, or a vasectomized partner). Exclusion Criteria: History of immunodeficiency. Known or suspected impairment of immunologic function including, but not limited to, clinically significant liver disease; diabetes mellitus; moderate to severe kidney impairment. History of Guillain-Barré syndrome. Malignancy, other than squamous cell or basal cell skin cancer. Autoimmune disease. History of asthma or reactive airways disease. Chronic cardiovascular and pulmonary disorder. Chronic metabolic diseases (including diabetes), renal dysfunction or hemoglobinopathies requiring regular medical follow-up or hospitalization during the preceding year. Use of immunosuppressive medication. Corticosteroid nasal sprays are permissible. Medical or psychiatric condition or occupational responsibilities that preclude subject compliance with the protocol. Inactivated vaccine 14 days prior to vaccination. Live, attenuated vaccines within 60 days of study. Use of investigational agents within 30 days prior to study. Receipt of blood products or immunoglobulin in the past 6 months. Donation of the equivalent of a unit of blood within 6 weeks prior to enrollment. Acute febrile illness on the day of vaccination. Pregnant or lactating women. Known allergies to any component of the vaccine, including thimerosal. History of allergy to eggs or egg products. Any condition that, in the opinion of the investigator, might interfere with study objectives.